18138636 has 18 divisors (see below), whose sum is σ = 45850532. Its totient is φ = 6046200.

The previous prime is 18138629. The next prime is 18138649. The reversal of 18138636 is 63683181.

18138636 is a `hidden beast` number, since 1 + 8 + 13 + 8 + 636 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 503851 = 18138636 / (1 + 8 + 1 + 3 + 8 + 6 + 3 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 18138636.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 251890 + ... + 251961.

Almost surely, 2^18138636 is an apocalyptic number.

It is an amenable number.

18138636 is an abundant number, since it is smaller than the sum of its proper divisors (27711896).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18138636 is a wasteful number, since it uses less digits than its factorization.

18138636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 503861 (or 503856 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 18138636 is about 4258.9477573692. The cubic root of 18138636 is about 262.7452510652.

The spelling of 18138636 in words is "eighteen million, one hundred thirty-eight thousand, six hundred thirty-six".