251278321321 has 2 divisors, whose sum is σ = 251278321322. Its totient is φ = 251278321320.

The previous prime is 251278321289. The next prime is 251278321351. The reversal of 251278321321 is 123123872152.

251278321321 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 230173495696 + 21104825625 = 479764^2 + 145275^2 .

It is a cyclic number.

It is not a de Polignac number, because 251278321321 - 2⁵ = 251278321289 is a prime.

It is not a weakly prime, because it can be changed into another prime (251278321351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125639160660 + 125639160661.

It is an arithmetic number, because the mean of its divisors is an integer number (125639160661).

Almost surely, 2^251278321321 is an apocalyptic number.

It is an amenable number.

251278321321 is a deficient number, since it is larger than the sum of its proper divisors (1).

251278321321 is an equidigital number, since it uses as much as digits as its factorization.

251278321321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40320, while the sum is 37.

The spelling of 251278321321 in words is "two hundred fifty-one billion, two hundred seventy-eight million, three hundred twenty-one thousand, three hundred twenty-one".