756561681 has 16 divisors (see below), whose sum is σ = 1151126400. Its totient is φ = 490742064.

The previous prime is 756561667. The next prime is 756561691. The reversal of 756561681 is 186165657.

756561681 is a `hidden beast` number, since 7 + 5 + 6 + 561 + 6 + 81 = 666.

It is not a de Polignac number, because 756561681 - 2⁵ = 756561649 is a prime.

It is a super-2 number, since 2×756561681² = 1144771154315091522, which contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (756561601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 377661 + ... + 379658.

It is an arithmetic number, because the mean of its divisors is an integer number (71945400).

Almost surely, 2^756561681 is an apocalyptic number.

It is an amenable number.

756561681 is a deficient number, since it is larger than the sum of its proper divisors (394564719).

756561681 is a wasteful number, since it uses less digits than its factorization.

756561681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 757365 (or 757359 counting only the distinct ones).

The product of its digits is 302400, while the sum is 45.

The square root of 756561681 is about 27505.6663435009. Note that the first 3 decimals coincide. The cubic root of 756561681 is about 911.2022434286.

The spelling of 756561681 in words is "seven hundred fifty-six million, five hundred sixty-one thousand, six hundred eighty-one".