681934157 has 2 divisors, whose sum is σ = 681934158. Its totient is φ = 681934156.

The previous prime is 681934129. The next prime is 681934163. The reversal of 681934157 is 751439186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 602260681 + 79673476 = 24541^2 + 8926^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681934157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681934117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340967078 + 340967079.

It is an arithmetic number, because the mean of its divisors is an integer number (340967079).

Almost surely, 2^681934157 is an apocalyptic number.

It is an amenable number.

681934157 is a deficient number, since it is larger than the sum of its proper divisors (1).

681934157 is an equidigital number, since it uses as much as digits as its factorization.

681934157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 181440, while the sum is 44.

The square root of 681934157 is about 26113.8690545848. The cubic root of 681934157 is about 880.1988862625.

The spelling of 681934157 in words is "six hundred eighty-one million, nine hundred thirty-four thousand, one hundred fifty-seven".