12656439492921 has 27 divisors (see below), whose sum is σ = 21266387810031. Its totient is φ = 7232208447744.

The previous prime is 12656439492833. The next prime is 12656439492989. The reversal of 12656439492921 is 12929493465621.

The square root of 12656439492921 is 3557589.

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

12656439492921 is a `hidden beast` number, since 1 + 2 + 6 + 56 + 4 + 3 + 9 + 492 + 92 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 10000843332921 + 2655596160000 = 3162411^2 + 1629600^2 .

It is not a de Polignac number, because 12656439492921 - 2¹⁵ = 12656439460153 is a prime.

It is a super-2 number, since 2×12656439492921² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (12656439492721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 74624665 + ... + 74794073.

Almost surely, 2^{12656439492921} is an apocalyptic number.

12656439492921 is the 3557589-th square number.

12656439492921 is the 1778795-th centered octagonal number.

It is an amenable number.

12656439492921 is a deficient number, since it is larger than the sum of its proper divisors (8609948317110).

12656439492921 is an frugal number, since it uses more digits than its factorization.

12656439492921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338838 (or 169419 counting only the distinct ones).

The product of its digits is 50388480, while the sum is 63.

The spelling of 12656439492921 in words is "twelve trillion, six hundred fifty-six billion, four hundred thirty-nine million, four hundred ninety-two thousand, nine hundred twenty-one".