18987990 has 48 divisors (see below), whose sum is σ = 53015472. Its totient is φ = 4339776.

The previous prime is 18987977. The next prime is 18988003. The reversal of 18987990 is 9978981.

It is an interprime number because it is at equal distance from previous prime (18987977) and next prime (18988003).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4989 + ... + 7928.

It is an arithmetic number, because the mean of its divisors is an integer number (1104489).

Almost surely, 2^18987990 is an apocalyptic number.

18987990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18987990 is an abundant number, since it is smaller than the sum of its proper divisors (34027482).

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

18987990 is a wasteful number, since it uses less digits than its factorization.

18987990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12941 (or 12934 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 51.

The square root of 18987990 is about 4357.5210842863. The cubic root of 18987990 is about 266.7839293307.

Subtracting from 18987990 its reverse (9978981), we obtain a palindrome (9009009).

The spelling of 18987990 in words is "eighteen million, nine hundred eighty-seven thousand, nine hundred ninety".