251640407225 has 12 divisors (see below), whose sum is σ = 312108020460. Its totient is φ = 201264638400.

The previous prime is 251640407129. The next prime is 251640407237. The reversal of 251640407225 is 522704046152.

It can be written as a sum of positive squares in 6 ways, for example, as 12858652816 + 238781754409 = 113396^2 + 488653^2 .

It is not a de Polignac number, because 251640407225 - 2³⁴ = 234460538041 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1084346 + ... + 1295795.

It is an arithmetic number, because the mean of its divisors is an integer number (26009001705).

Almost surely, 2^251640407225 is an apocalyptic number.

251640407225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

251640407225 is a deficient number, since it is larger than the sum of its proper divisors (60467613235).

251640407225 is a wasteful number, since it uses less digits than its factorization.

251640407225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2384380 (or 2384375 counting only the distinct ones).

The product of its (nonzero) digits is 134400, while the sum is 38.

The spelling of 251640407225 in words is "two hundred fifty-one billion, six hundred forty million, four hundred seven thousand, two hundred twenty-five".