18816638974225 has 9 divisors (see below), whose sum is σ = 23332659222523. Its totient is φ = 15053293828120.

The previous prime is 18816638974219. The next prime is 18816638974249. The reversal of 18816638974225 is 52247983661881.

The square root of 18816638974225 is 4337815.

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

It can be written as a sum of positive squares in only one way, i.e., 6773990030721 + 12042648943504 = 2602689^2 + 3470252^2 .

It is a de Polignac number, because none of the positive numbers 2^k-18816638974225 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 21255294 + ... + 22122856.

Almost surely, 2^{18816638974225} is an apocalyptic number.

18816638974225 is the 4337815-th square number.

18816638974225 is the 2168908-th centered octagonal number.

It is an amenable number.

18816638974225 is a deficient number, since it is larger than the sum of its proper divisors (4516020248298).

18816638974225 is an frugal number, since it uses more digits than its factorization.

18816638974225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1735136 (or 867568 counting only the distinct ones).

The product of its digits is 278691840, while the sum is 70.

The spelling of 18816638974225 in words is "eighteen trillion, eight hundred sixteen billion, six hundred thirty-eight million, nine hundred seventy-four thousand, two hundred twenty-five".