18091908 has 18 divisors (see below), whose sum is σ = 45732414. Its totient is φ = 6030624.

The previous prime is 18091891. The next prime is 18091919. The reversal of 18091908 is 80919081.

It can be written as a sum of positive squares in only one way, i.e., 17994564 + 97344 = 4242^2 + 312^2 .

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: 502553 = 18091908 / (1 + 8 + 0 + 9 + 1 + 9 + 0 + 8).

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, 251241 + ... + 251312.

Almost surely, 2^18091908 is an apocalyptic number.

18091908 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

18091908 is an abundant number, since it is smaller than the sum of its proper divisors (27640506).

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

18091908 is a wasteful number, since it uses less digits than its factorization.

18091908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 502563 (or 502558 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 36.

The square root of 18091908 is about 4253.4583576191. The cubic root of 18091908 is about 262.5194325750.

The spelling of 18091908 in words is "eighteen million, ninety-one thousand, nine hundred eight".