251612681 has 2 divisors, whose sum is σ = 251612682. Its totient is φ = 251612680.

The previous prime is 251612633. The next prime is 251612717. The reversal of 251612681 is 186216152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 246772681 + 4840000 = 15709^2 + 2200^2 .

It is a cyclic number.

It is not a de Polignac number, because 251612681 - 2²⁶ = 184503817 is a prime.

It is a super-2 number, since 2×251612681² = 126617882480015522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (251612281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125806340 + 125806341.

It is an arithmetic number, because the mean of its divisors is an integer number (125806341).

Almost surely, 2^251612681 is an apocalyptic number.

It is an amenable number.

251612681 is a deficient number, since it is larger than the sum of its proper divisors (1).

251612681 is an equidigital number, since it uses as much as digits as its factorization.

251612681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 32.

The square root of 251612681 is about 15862.3037734120. The cubic root of 251612681 is about 631.3121898537.

The spelling of 251612681 in words is "two hundred fifty-one million, six hundred twelve thousand, six hundred eighty-one".