681813931 has 2 divisors, whose sum is σ = 681813932. Its totient is φ = 681813930.

The previous prime is 681813901. The next prime is 681813953. The reversal of 681813931 is 139318186.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681813931 is a prime.

It is a super-2 number, since 2×681813931² = 929740473011345522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (681813901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340906965 + 340906966.

It is an arithmetic number, because the mean of its divisors is an integer number (340906966).

Almost surely, 2^681813931 is an apocalyptic number.

681813931 is a deficient number, since it is larger than the sum of its proper divisors (1).

681813931 is an equidigital number, since it uses as much as digits as its factorization.

681813931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 40.

The square root of 681813931 is about 26111.5669962567. The cubic root of 681813931 is about 880.1471564340.

The spelling of 681813931 in words is "six hundred eighty-one million, eight hundred thirteen thousand, nine hundred thirty-one".