12638031561 has 15 divisors (see below), whose sum is σ = 18880546333. Its totient is φ = 8424679860.

The previous prime is 12638031541. The next prime is 12638031589. The reversal of 12638031561 is 16513083621.

The square root of 12638031561 is 112419.

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

12638031561 is a `hidden beast` number, since 1 + 2 + 63 + 8 + 0 + 31 + 561 = 666.

It is not a de Polignac number, because 12638031561 - 2⁵ = 12638031529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12638031541) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 1005526 + ... + 1018016.

Almost surely, 2^12638031561 is an apocalyptic number.

12638031561 is the 112419-th square number.

12638031561 is the 56210-th centered octagonal number.

It is an amenable number.

12638031561 is a deficient number, since it is larger than the sum of its proper divisors (6242514772).

12638031561 is an frugal number, since it uses more digits than its factorization.

12638031561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24994 (or 12494 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

Multiplying 12638031561 by its sum of digits (36), we get a square (454969136196 = 674514²).

The spelling of 12638031561 in words is "twelve billion, six hundred thirty-eight million, thirty-one thousand, five hundred sixty-one".