18801990 has 64 divisors (see below), whose sum is σ = 50803200. Its totient is φ = 4947552.

The previous prime is 18801989. The next prime is 18801997. The reversal of 18801990 is 9910881.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18801997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21991 + ... + 22829.

It is an arithmetic number, because the mean of its divisors is an integer number (793800).

Almost surely, 2^18801990 is an apocalyptic number.

18801990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 18801990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25401600).

18801990 is an abundant number, since it is smaller than the sum of its proper divisors (32001210).

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

18801990 is a wasteful number, since it uses less digits than its factorization.

18801990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 938 (or 932 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 36.

The square root of 18801990 is about 4336.1261513014. The cubic root of 18801990 is about 265.9099606690.

It can be divided in two parts, 18801 and 990, that added together give a palindrome (19791).

The spelling of 18801990 in words is "eighteen million, eight hundred one thousand, nine hundred ninety".