18933990 has 16 divisors (see below), whose sum is σ = 45441648. Its totient is φ = 5049056.

The previous prime is 18933977. The next prime is 18934001. The reversal of 18933990 is 9933981.

It is a happy number.

It is a Curzon number.

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, 315537 + ... + 315596.

It is an arithmetic number, because the mean of its divisors is an integer number (2840103).

Almost surely, 2^18933990 is an apocalyptic number.

18933990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18933990 is an abundant number, since it is smaller than the sum of its proper divisors (26507658).

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

18933990 is a wasteful number, since it uses less digits than its factorization.

18933990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 631143.

The product of its (nonzero) digits is 52488, while the sum is 42.

The square root of 18933990 is about 4351.3204892308. The cubic root of 18933990 is about 266.5307866769.

Subtracting from 18933990 its reverse (9933981), we obtain a palindrome (9000009).

The spelling of 18933990 in words is "eighteen million, nine hundred thirty-three thousand, nine hundred ninety".