251525640 has 32 divisors (see below), whose sum is σ = 754577280. Its totient is φ = 67073472.

The previous prime is 251525639. The next prime is 251525647. The reversal of 251525640 is 46525152.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 251525598 and 251525607.

It is not an unprimeable number, because it can be changed into a prime (251525647) 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 in 7 ways as a sum of consecutive naturals, for example, 1047904 + ... + 1048143.

It is an arithmetic number, because the mean of its divisors is an integer number (23580540).

Almost surely, 2^251525640 is an apocalyptic number.

251525640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

251525640 is an abundant number, since it is smaller than the sum of its proper divisors (503051640).

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

251525640 is a wasteful number, since it uses less digits than its factorization.

251525640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2096061 (or 2096057 counting only the distinct ones).

The product of its (nonzero) digits is 12000, while the sum is 30.

The square root of 251525640 is about 15859.5598930109. The cubic root of 251525640 is about 631.2393843263.

The spelling of 251525640 in words is "two hundred fifty-one million, five hundred twenty-five thousand, six hundred forty".