12172929561 has 135 divisors (see below), whose sum is σ = 21098271117. Its totient is φ = 6990572160.

The previous prime is 12172929551. The next prime is 12172929563. The reversal of 12172929561 is 16592927121.

The square root of 12172929561 is 110331.

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

12172929561 is a `hidden beast` number, since 1 + 217 + 292 + 95 + 61 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 8108102025 + 4064827536 = 90045^2 + 63756^2 .

It is not a de Polignac number, because 12172929561 - 2⁵ = 12172929529 is a prime.

Its product of digits (136080) is a multiple of the sum of its prime divisors (80).

It is not an unprimeable number, because it can be changed into a prime (12172929563) by changing a digit.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 296900701 + ... + 296900741.

Almost surely, 2^12172929561 is an apocalyptic number.

12172929561 is the 110331-st square number.

12172929561 is the 55166-th centered octagonal number.

It is an amenable number.

12172929561 is a deficient number, since it is larger than the sum of its proper divisors (8925341556).

12172929561 is an equidigital number, since it uses as much as digits as its factorization.

12172929561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166 (or 80 counting only the distinct ones).

The product of its digits is 136080, while the sum is 45.

The spelling of 12172929561 in words is "twelve billion, one hundred seventy-two million, nine hundred twenty-nine thousand, five hundred sixty-one".