9156439973521 has 3 divisors (see below), whose sum is σ = 9156442999483. Its totient is φ = 9156436947560.

The previous prime is 9156439973507. The next prime is 9156439973573. The reversal of 9156439973521 is 1253799346519.

The square root of 9156439973521 is 3025961.

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., 267455499921 + 8888984473600 = 517161^2 + 2981440^2 .

It is not a de Polignac number, because 9156439973521 - 2⁵ = 9156439973489 is a prime.

It is a super-2 number, since 2×9156439973521² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9156439973591) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1512981 + ... + 4538941.

Almost surely, 2^{9156439973521} is an apocalyptic number.

9156439973521 is the 3025961-st square number.

9156439973521 is the 1512981-st centered octagonal number.

It is an amenable number.

9156439973521 is a deficient number, since it is larger than the sum of its proper divisors (3025962).

9156439973521 is an frugal number, since it uses more digits than its factorization.

9156439973521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6051922 (or 3025961 counting only the distinct ones).

The product of its digits is 55112400, while the sum is 64.

Multiplying 9156439973521 by its sum of digits (64), we get a square (586012158305344 = 24207688²).

The spelling of 9156439973521 in words is "nine trillion, one hundred fifty-six billion, four hundred thirty-nine million, nine hundred seventy-three thousand, five hundred twenty-one".