18909218 has 16 divisors (see below), whose sum is σ = 30888000. Its totient is φ = 8647632.

The previous prime is 18909173. The next prime is 18909221. The reversal of 18909218 is 81290981.

It is a Harshad number since it is a multiple of its sum of digits (38).

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7478 + ... + 9681.

It is an arithmetic number, because the mean of its divisors is an integer number (1930500).

Almost surely, 2^18909218 is an apocalyptic number.

18909218 is a deficient number, since it is larger than the sum of its proper divisors (11978782).

18909218 is a wasteful number, since it uses less digits than its factorization.

18909218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17209.

The product of its (nonzero) digits is 10368, while the sum is 38.

The square root of 18909218 is about 4348.4730653414. The cubic root of 18909218 is about 266.4144987705.

The spelling of 18909218 in words is "eighteen million, nine hundred nine thousand, two hundred eighteen".