18871920 has 80 divisors (see below), whose sum is σ = 65010720. Its totient is φ = 5031936.

The previous prime is 18871913. The next prime is 18871927. The reversal of 18871920 is 2917881.

It is an interprime number because it is at equal distance from previous prime (18871913) and next prime (18871927).

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×18871920² = 712298728972800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18871927) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2209 + ... + 6528.

It is an arithmetic number, because the mean of its divisors is an integer number (812634).

Almost surely, 2^18871920 is an apocalyptic number.

18871920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18871920 is an abundant number, since it is smaller than the sum of its proper divisors (46138800).

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

18871920 is a wasteful number, since it uses less digits than its factorization.

18871920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8759 (or 8747 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 18871920 is about 4344.1823166161. The cubic root of 18871920 is about 266.2392179724.

It can be divided in two parts, 18871 and 920, that added together give a palindrome (19791).

The spelling of 18871920 in words is "eighteen million, eight hundred seventy-one thousand, nine hundred twenty".