18918639 has 12 divisors (see below), whose sum is σ = 27509872. Its totient is φ = 12528000.

The previous prime is 18918619. The next prime is 18918709. The reversal of 18918639 is 93681981.

18918639 is a `hidden beast` number, since 1 + 8 + 9 + 1 + 8 + 639 = 666.

It is not a de Polignac number, because 18918639 - 2¹² = 18914543 is a prime.

It is a super-2 number, since 2×18918639² = 715829803224642, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18918594 and 18918603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18918619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5602 + ... + 8319.

Almost surely, 2^18918639 is an apocalyptic number.

18918639 is a deficient number, since it is larger than the sum of its proper divisors (8591233).

18918639 is a wasteful number, since it uses less digits than its factorization.

18918639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14078 (or 14075 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 18918639 is about 4349.5561842560. The cubic root of 18918639 is about 266.4587360006.

It can be divided in two parts, 189186 and 39, that added together give a square (189225 = 435²).

The spelling of 18918639 in words is "eighteen million, nine hundred eighteen thousand, six hundred thirty-nine".