656976712681 has 3 divisors (see below), whose sum is σ = 656977523223. Its totient is φ = 656975902140.

The previous prime is 656976712669. The next prime is 656976712741. The reversal of 656976712681 is 186217679656.

The square root of 656976712681 is 810541.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 420021944281 + 236954768400 = 648091^2 + 486780^2 .

It is not a de Polignac number, because 656976712681 - 2⁵ = 656976712649 is a prime.

It is a super-3 number, since 3×656976712681³ (a number of 36 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (656976716681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 405271 + ... + 1215811.

It is an arithmetic number, because the mean of its divisors is an integer number (218992507741).

Almost surely, 2^656976712681 is an apocalyptic number.

656976712681 is the 810541-st square number.

656976712681 is the 405271-st centered octagonal number.

It is an amenable number.

656976712681 is a deficient number, since it is larger than the sum of its proper divisors (810542).

656976712681 is an frugal number, since it uses more digits than its factorization.

656976712681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1621082 (or 810541 counting only the distinct ones).

The product of its digits is 45722880, while the sum is 64.

Multiplying 656976712681 by its sum of digits (64), we get a square (42046509611584 = 6484328²).

The spelling of 656976712681 in words is "six hundred fifty-six billion, nine hundred seventy-six million, seven hundred twelve thousand, six hundred eighty-one".