251166357225 has 405 divisors, whose sum is σ = 569464467957. Its totient is φ = 109117653120.

The previous prime is 251166357179. The next prime is 251166357229. The reversal of 251166357225 is 522753661152.

It is a happy number.

The square root of 251166357225 is 501165.

It is a perfect power (a square), and thus also a powerful number.

251166357225 is a `hidden beast` number, since 2 + 5 + 1 + 1 + 6 + 635 + 7 + 2 + 2 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 23843374569 + 227322982656 = 154413^2 + 476784^2 .

It is a tau number, because it is divible by the number of its divisors (405).

It is not a de Polignac number, because 251166357225 - 2⁹ = 251166356713 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (251166357229) by changing a digit.

It is a polite number, since it can be written in 404 ways as a sum of consecutive naturals, for example, 5841078054 + ... + 5841078096.

Almost surely, 2^251166357225 is an apocalyptic number.

251166357225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

251166357225 is the 501165-th square number.

251166357225 is the 250583-rd centered octagonal number.

It is an amenable number.

251166357225 is an abundant number, since it is smaller than the sum of its proper divisors (318298110732).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

251166357225 is an equidigital number, since it uses as much as digits as its factorization.

251166357225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196 (or 95 counting only the distinct ones).

The product of its digits is 756000, while the sum is 45.

The spelling of 251166357225 in words is "two hundred fifty-one billion, one hundred sixty-six million, three hundred fifty-seven thousand, two hundred twenty-five".