18690991225 has 27 divisors (see below), whose sum is σ = 23852436237. Its totient is φ = 14528976480.

The previous prime is 18690991213. The next prime is 18690991229. The reversal of 18690991225 is 52219909681.

The square root of 18690991225 is 136715.

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

It can be written as a sum of positive squares in 4 ways, for example, as 1774347129 + 16916644096 = 42123^2 + 130064^2 .

It is not a de Polignac number, because 18690991225 - 2⁷ = 18690991097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18690991229) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 25291906 + ... + 25292644.

Almost surely, 2^18690991225 is an apocalyptic number.

18690991225 is the 136715-th square number.

18690991225 is the 68358-th centered octagonal number.

It is an amenable number.

18690991225 is a deficient number, since it is larger than the sum of its proper divisors (5161445012).

18690991225 is an frugal number, since it uses more digits than its factorization.

18690991225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1562 (or 781 counting only the distinct ones).

The product of its (nonzero) digits is 699840, while the sum is 52.

The spelling of 18690991225 in words is "eighteen billion, six hundred ninety million, nine hundred ninety-one thousand, two hundred twenty-five".