391791362021 has 2 divisors, whose sum is σ = 391791362022. Its totient is φ = 391791362020.

The previous prime is 391791362003. The next prime is 391791362063. The reversal of 391791362021 is 120263197193.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 362964076225 + 28827285796 = 602465^2 + 169786^2 .

It is a cyclic number.

It is not a de Polignac number, because 391791362021 - 2¹⁰ = 391791360997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391791362071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195895681010 + 195895681011.

It is an arithmetic number, because the mean of its divisors is an integer number (195895681011).

Almost surely, 2^391791362021 is an apocalyptic number.

It is an amenable number.

391791362021 is a deficient number, since it is larger than the sum of its proper divisors (1).

391791362021 is an equidigital number, since it uses as much as digits as its factorization.

391791362021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 122472, while the sum is 44.

The spelling of 391791362021 in words is "three hundred ninety-one billion, seven hundred ninety-one million, three hundred sixty-two thousand, twenty-one".