290 (number)

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← 200 210 220 230 240 250 260 270 280 290 → List of numbers — Integers ← 0 100 200 300 400 500 600 700 800 900 →
Ordinal	two hundred [and] ninetieth
Cardinal	two hundred [and] ninety
Factorization
Roman numeral	CCXC
Binary	100100010
Hexadecimal	122

290 is the natural number after 289 and before 291.

[edit] In mathematics

The product of three primes, 290 is a sphenic number, and the sum of four consecutive primes (67 + 71 + 73 + 79). The sum of the squares of the divisors of 17 is 290.

Not only is it a nontotient and a noncototient, it is also an untouchable number.

290 is the 16th member of the Mian-Chowla sequence; it can't be obtained as the sum of any two previous terms in the sequence.

See also Conway's 290 theorem.

[edit] In other fields

• "290" is one of Naoki Maeda's pseudonyms.
• "290" was the shipyard number of the CSS Alabama

See also the year 290.

[edit] 291 to 299

• Two hundred [and] ninety-one 291 = 3·97
• Two hundred [and] ninety-two 292 = 2²·73, noncototient, untouchable number. The continued fraction representation of pi is [3; 7, 15, 1, 292, 1, 1, 1, 2...]; the convergent obtained by truncating before the surprisingly large term 292 yields the excellent rational approximation 355/113 to pi, repdigit in base 8 (444).
• Two hundred [and] ninety-three 293 prime, Sophie Germain prime, Chen prime, Eisenstein prime with no imaginary part, strictly non-palindromic number
• Two hundred [and] ninety-four 294 = 2·3·7²
• Two hundred [and] ninety-five 295 = 5·59, also, the numerical designation of seven spur routes of Interstate 95 in the United States.
• Two hundred [and] ninety-six 296 = 2³·37
• Two hundred [and] ninety-seven 297 = 3³·11, decagonal number, Kaprekar number
• Two hundred [and] ninety-eight 298 = 2·149, nontotient, noncototient
• Two hundred [and] ninety-nine 299 = 13·23, highly cototient number, self number, the twelfth cake number