18993990 has 16 divisors (see below), whose sum is σ = 45585648. Its totient is φ = 5065056.

The previous prime is 18993983. The next prime is 18994007. The reversal of 18993990 is 9939981.

It is a super-2 number, since 2×18993990² = 721543312240200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 316537 + ... + 316596.

It is an arithmetic number, because the mean of its divisors is an integer number (2849103).

Almost surely, 2^18993990 is an apocalyptic number.

18993990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18993990 is an abundant number, since it is smaller than the sum of its proper divisors (26591658).

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

18993990 is a wasteful number, since it uses less digits than its factorization.

18993990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 633143.

The product of its (nonzero) digits is 157464, while the sum is 48.

The square root of 18993990 is about 4358.2094947352. The cubic root of 18993990 is about 266.8120266527.

The spelling of 18993990 in words is "eighteen million, nine hundred ninety-three thousand, nine hundred ninety".