18381666 has 16 divisors (see below), whose sum is σ = 36806688. Its totient is φ = 6120000.

The previous prime is 18381647. The next prime is 18381677. The reversal of 18381666 is 66618381.

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, 7041 + ... + 9291.

It is an arithmetic number, because the mean of its divisors is an integer number (2300418).

Almost surely, 2^18381666 is an apocalyptic number.

18381666 is an abundant number, since it is smaller than the sum of its proper divisors (18425022).

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

18381666 is a wasteful number, since it uses less digits than its factorization.

18381666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3617.

The product of its digits is 41472, while the sum is 39.

The square root of 18381666 is about 4287.3845173952. The cubic root of 18381666 is about 263.9135104652.

The spelling of 18381666 in words is "eighteen million, three hundred eighty-one thousand, six hundred sixty-six".