18631431009 has 27 divisors (see below), whose sum is σ = 27171840787. Its totient is φ = 12302201616.

The previous prime is 18631430977. The next prime is 18631431011. The reversal of 18631431009 is 90013413681.

The square root of 18631431009 is 136497.

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

18631431009 is a `hidden beast` number, since 1 + 8 + 631 + 4 + 3 + 10 + 0 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 16948134225 + 1683296784 = 130185^2 + 41028^2 .

It is not a de Polignac number, because 18631431009 - 2⁵ = 18631430977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18631431019) 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, 70841812 + ... + 70842074.

Almost surely, 2^18631431009 is an apocalyptic number.

18631431009 is the 136497-th square number.

18631431009 is the 68249-th centered octagonal number.

It is an amenable number.

18631431009 is a deficient number, since it is larger than the sum of its proper divisors (8540409778).

18631431009 is an frugal number, since it uses more digits than its factorization.

18631431009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 878 (or 439 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

Multiplying 18631431009 by its sum of digits (36), we get a square (670731516324 = 818982²).

The spelling of 18631431009 in words is "eighteen billion, six hundred thirty-one million, four hundred thirty-one thousand, nine".