815923921931 has 2 divisors, whose sum is σ = 815923921932. Its totient is φ = 815923921930.

The previous prime is 815923921867. The next prime is 815923921949. The reversal of 815923921931 is 139129329518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 815923921931 - 2⁶ = 815923921867 is a prime.

It is a super-2 number, since 2×815923921931² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (815923921951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 407961960965 + 407961960966.

It is an arithmetic number, because the mean of its divisors is an integer number (407961960966).

Almost surely, 2^815923921931 is an apocalyptic number.

815923921931 is a deficient number, since it is larger than the sum of its proper divisors (1).

815923921931 is an equidigital number, since it uses as much as digits as its factorization.

815923921931 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1049760, while the sum is 53.

The spelling of 815923921931 in words is "eight hundred fifteen billion, nine hundred twenty-three million, nine hundred twenty-one thousand, nine hundred thirty-one".