251761 has 2 divisors, whose sum is σ = 251762. Its totient is φ = 251760.

The previous prime is 251737. The next prime is 251789. The reversal of 251761 is 167152.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 136161 + 115600 = 369^2 + 340^2 .

It is a cyclic number.

It is not a de Polignac number, because 251761 - 2¹⁵ = 218993 is a prime.

It is a super-2 number, since 2×251761² = 126767202242, which contains 22 as substring.

It is a Chen prime.

251761 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (251701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125880 + 125881.

It is an arithmetic number, because the mean of its divisors is an integer number (125881).

2²⁵¹⁷⁶¹ is an apocalyptic number.

It is an amenable number.

251761 is a deficient number, since it is larger than the sum of its proper divisors (1).

251761 is an equidigital number, since it uses as much as digits as its factorization.

251761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 420, while the sum is 22.

The square root of 251761 is about 501.7579097533. The cubic root of 251761 is about 63.1436212750.

The spelling of 251761 in words is "two hundred fifty-one thousand, seven hundred sixty-one".