321997863693251 has 2 divisors, whose sum is σ = 321997863693252. Its totient is φ = 321997863693250.

The previous prime is 321997863693241. The next prime is 321997863693299. The reversal of 321997863693251 is 152396368799123.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-321997863693251 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (321997863693241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160998931846625 + 160998931846626.

It is an arithmetic number, because the mean of its divisors is an integer number (160998931846626).

Almost surely, 2^{321997863693251} is an apocalyptic number.

321997863693251 is a deficient number, since it is larger than the sum of its proper divisors (1).

321997863693251 is an equidigital number, since it uses as much as digits as its factorization.

321997863693251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 793618560, while the sum is 74.

The spelling of 321997863693251 in words is "three hundred twenty-one trillion, nine hundred ninety-seven billion, eight hundred sixty-three million, six hundred ninety-three thousand, two hundred fifty-one".