21920100 has 72 divisors (see below), whose sum is σ = 65495808. Its totient is φ = 5654400.

The previous prime is 21920057. The next prime is 21920113. The reversal of 21920100 is 102912.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21920100.

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 8122 + ... + 10478.

It is an arithmetic number, because the mean of its divisors is an integer number (909664).

Almost surely, 2^21920100 is an apocalyptic number.

21920100 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 21920100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32747904).

21920100 is an abundant number, since it is smaller than the sum of its proper divisors (43575708).

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

21920100 is a wasteful number, since it uses less digits than its factorization.

21920100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2405 (or 2398 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 21920100 is about 4681.8906437464. The cubic root of 21920100 is about 279.8643049977.

The spelling of 21920100 in words is "twenty-one million, nine hundred twenty thousand, one hundred".