20181920 has 48 divisors (see below), whose sum is σ = 52018848. Its totient is φ = 7338240.

The previous prime is 20181859. The next prime is 20181937. The reversal of 20181920 is 2918102.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 3974 + ... + 7493.

It is an arithmetic number, because the mean of its divisors is an integer number (1083726).

Almost surely, 2^20181920 is an apocalyptic number.

20181920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20181920 is an abundant number, since it is smaller than the sum of its proper divisors (31836928).

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

20181920 is a wasteful number, since it uses less digits than its factorization.

20181920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11493 (or 11485 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 20181920 is about 4492.4291869767. The cubic root of 20181920 is about 272.2622902442.

The spelling of 20181920 in words is "twenty million, one hundred eighty-one thousand, nine hundred twenty".