21920880 has 80 divisors (see below), whose sum is σ = 68522400. Its totient is φ = 5796864.

The previous prime is 21920869. The next prime is 21920887. The reversal of 21920880 is 8802912.

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

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21920887) 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 15 ways as a sum of consecutive naturals, for example, 35454 + ... + 36066.

It is an arithmetic number, because the mean of its divisors is an integer number (856530).

Almost surely, 2^21920880 is an apocalyptic number.

21920880 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 21920880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34261200).

21920880 is an abundant number, since it is smaller than the sum of its proper divisors (46601520).

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

21920880 is a wasteful number, since it uses less digits than its factorization.

21920880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 778 (or 772 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 21920880 is about 4681.9739426870. The cubic root of 21920880 is about 279.8676245016.

The spelling of 21920880 in words is "twenty-one million, nine hundred twenty thousand, eight hundred eighty".