251438372640 has 1920 divisors, whose sum is σ = 1178210880000. Its totient is φ = 50039119872.

The previous prime is 251438372617. The next prime is 251438372671. The reversal of 251438372640 is 46273834152.

251438372640 is a `hidden beast` number, since 2 + 5 + 1 + 4 + 383 + 7 + 264 + 0 = 666.

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

It is an unprimeable number.

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 319 ways as a sum of consecutive naturals, for example, 1097984046 + ... + 1097984274.

It is an arithmetic number, because the mean of its divisors is an integer number (613651500).

Almost surely, 2^251438372640 is an apocalyptic number.

251438372640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 251438372640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (589105440000).

251438372640 is an abundant number, since it is smaller than the sum of its proper divisors (926772507360).

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

251438372640 is a wasteful number, since it uses less digits than its factorization.

251438372640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 309 (or 278 counting only the distinct ones).

The product of its (nonzero) digits is 967680, while the sum is 45.

The spelling of 251438372640 in words is "two hundred fifty-one billion, four hundred thirty-eight million, three hundred seventy-two thousand, six hundred forty".