18681990 has 32 divisors (see below), whose sum is σ = 45347040. Its totient is φ = 4925184.

The previous prime is 18681989. The next prime is 18682009. The reversal of 18681990 is 9918681.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 829 + ... + 6168.

It is an arithmetic number, because the mean of its divisors is an integer number (1417095).

Almost surely, 2^18681990 is an apocalyptic number.

18681990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18681990 is an abundant number, since it is smaller than the sum of its proper divisors (26665050).

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

18681990 is a wasteful number, since it uses less digits than its factorization.

18681990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7096.

The product of its (nonzero) digits is 31104, while the sum is 42.

The square root of 18681990 is about 4322.2667664086. The cubic root of 18681990 is about 265.3430468879.

The spelling of 18681990 in words is "eighteen million, six hundred eighty-one thousand, nine hundred ninety".