18881920 has 64 divisors (see below), whose sum is σ = 45667440. Its totient is φ = 7464960.

The previous prime is 18881909. The next prime is 18881957. The reversal of 18881920 is 2918881.

It is a tau number, because it is divible by the number of its divisors (64).

It is a self number, because there is not a number n which added to its sum of digits gives 18881920.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 104230 + ... + 104410.

Almost surely, 2^18881920 is an apocalyptic number.

18881920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18881920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22833720).

18881920 is an abundant number, since it is smaller than the sum of its proper divisors (26785520).

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

18881920 is a wasteful number, since it uses less digits than its factorization.

18881920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363 (or 351 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 18881920 is about 4345.3331287716. Note that the first 3 decimals coincide. The cubic root of 18881920 is about 266.2862353058.

The spelling of 18881920 in words is "eighteen million, eight hundred eighty-one thousand, nine hundred twenty".