18909639 has 24 divisors (see below), whose sum is σ = 32590320. Its totient is φ = 10804752.

The previous prime is 18909629. The next prime is 18909673. The reversal of 18909639 is 93690981.

18909639 is a `hidden beast` number, since 1 + 8 + 9 + 0 + 9 + 639 = 666.

It is not a de Polignac number, because 18909639 - 2⁴ = 18909623 is a prime.

It is a super-2 number, since 2×18909639² = 715148894220642, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 18909594 and 18909603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18909619) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5824 + ... + 8469.

It is an arithmetic number, because the mean of its divisors is an integer number (1357930).

Almost surely, 2^18909639 is an apocalyptic number.

18909639 is a deficient number, since it is larger than the sum of its proper divisors (13680681).

18909639 is a wasteful number, since it uses less digits than its factorization.

18909639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14316 (or 14303 counting only the distinct ones).

The product of its (nonzero) digits is 104976, while the sum is 45.

The square root of 18909639 is about 4348.5214728687. The cubic root of 18909639 is about 266.4164759309.

The spelling of 18909639 in words is "eighteen million, nine hundred nine thousand, six hundred thirty-nine".