21919920 has 240 divisors, whose sum is σ = 81637632. Its totient is φ = 4815360.

The previous prime is 21919903. The next prime is 21919927. The reversal of 21919920 is 2991912.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21919927) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 953029 + ... + 953051.

Almost surely, 2^21919920 is an apocalyptic number.

21919920 is a gapful number since it is divisible by the number (20) 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 21919920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40818816).

21919920 is an abundant number, since it is smaller than the sum of its proper divisors (59717712).

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

21919920 is a wasteful number, since it uses less digits than its factorization.

21919920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88 (or 63 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 33.

The square root of 21919920 is about 4681.8714207035. The cubic root of 21919920 is about 279.8635389472.

The spelling of 21919920 in words is "twenty-one million, nine hundred nineteen thousand, nine hundred twenty".