765631681 has 2 divisors, whose sum is σ = 765631682. Its totient is φ = 765631680.

The previous prime is 765631637. The next prime is 765631717. The reversal of 765631681 is 186136567.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 451775025 + 313856656 = 21255^2 + 17716^2 .

It is a cyclic number.

It is not a de Polignac number, because 765631681 - 2¹⁵ = 765598913 is a prime.

It is a super-2 number, since 2×765631681² = 1172383741901771522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (765631621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 382815840 + 382815841.

It is an arithmetic number, because the mean of its divisors is an integer number (382815841).

Almost surely, 2^765631681 is an apocalyptic number.

It is an amenable number.

765631681 is a deficient number, since it is larger than the sum of its proper divisors (1).

765631681 is an equidigital number, since it uses as much as digits as its factorization.

765631681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 181440, while the sum is 43.

The square root of 765631681 is about 27670.0502529359. The cubic root of 765631681 is about 914.8290884854.

The spelling of 765631681 in words is "seven hundred sixty-five million, six hundred thirty-one thousand, six hundred eighty-one".