251278321320 has 96 divisors (see below), whose sum is σ = 879474141000. Its totient is φ = 61853124096.

The previous prime is 251278321289. The next prime is 251278321321. The reversal of 251278321320 is 23123872152.

251278321320 is a `hidden beast` number, since 2 + 5 + 1 + 2 + 7 + 8 + 321 + 320 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 219546599364 + 31731721956 = 468558^2 + 178134^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (251278321321) 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, 26841295 + ... + 26850654.

Almost surely, 2^251278321320 is an apocalyptic number.

251278321320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

251278321320 is an abundant number, since it is smaller than the sum of its proper divisors (628195819680).

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

251278321320 is a wasteful number, since it uses less digits than its factorization.

251278321320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53691979 (or 53691972 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The spelling of 251278321320 in words is "two hundred fifty-one billion, two hundred seventy-eight million, three hundred twenty-one thousand, three hundred twenty".