18405990 has 24 divisors (see below), whose sum is σ = 47855808. Its totient is φ = 4908240.

The previous prime is 18405977. The next prime is 18405991. The reversal of 18405990 is 9950481.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18405991) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 102166 + ... + 102345.

It is an arithmetic number, because the mean of its divisors is an integer number (1993992).

Almost surely, 2^18405990 is an apocalyptic number.

18405990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18405990 is an abundant number, since it is smaller than the sum of its proper divisors (29449818).

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

18405990 is a wasteful number, since it uses less digits than its factorization.

18405990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204524 (or 204521 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 18405990 is about 4290.2202740652. The cubic root of 18405990 is about 264.0298692100.

The spelling of 18405990 in words is "eighteen million, four hundred five thousand, nine hundred ninety".