251542991601 has 24 divisors (see below), whose sum is σ = 400219050816. Its totient is φ = 150970191840.

The previous prime is 251542991507. The next prime is 251542991617. The reversal of 251542991601 is 106199245152.

251542991601 is a `hidden beast` number, since 2 + 5 + 1 + 542 + 99 + 16 + 0 + 1 = 666.

It is not a de Polignac number, because 251542991601 - 2¹⁰ = 251542990577 is a prime.

It is not an unprimeable number, because it can be changed into a prime (251542998601) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12323970 + ... + 12344363.

It is an arithmetic number, because the mean of its divisors is an integer number (16675793784).

Almost surely, 2^251542991601 is an apocalyptic number.

It is an amenable number.

251542991601 is a deficient number, since it is larger than the sum of its proper divisors (148676059215).

251542991601 is a wasteful number, since it uses less digits than its factorization.

251542991601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24668453 (or 24668450 counting only the distinct ones).

The product of its (nonzero) digits is 194400, while the sum is 45.

The spelling of 251542991601 in words is "two hundred fifty-one billion, five hundred forty-two million, nine hundred ninety-one thousand, six hundred one".