251231334401561 has 2 divisors, whose sum is σ = 251231334401562. Its totient is φ = 251231334401560.

The previous prime is 251231334401497. The next prime is 251231334401591. The reversal of 251231334401561 is 165104433132152.

251231334401561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 247381968881161 + 3849365520400 = 15728381^2 + 1961980^2 .

It is a cyclic number.

It is not a de Polignac number, because 251231334401561 - 2⁶ = 251231334401497 is a prime.

It is not a weakly prime, because it can be changed into another prime (251231334401591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125615667200780 + 125615667200781.

It is an arithmetic number, because the mean of its divisors is an integer number (125615667200781).

Almost surely, 2^{251231334401561} is an apocalyptic number.

It is an amenable number.

251231334401561 is a deficient number, since it is larger than the sum of its proper divisors (1).

251231334401561 is an equidigital number, since it uses as much as digits as its factorization.

251231334401561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 259200, while the sum is 41.

The spelling of 251231334401561 in words is "two hundred fifty-one trillion, two hundred thirty-one billion, three hundred thirty-four million, four hundred one thousand, five hundred sixty-one".