21802920 has 64 divisors (see below), whose sum is σ = 67530240. Its totient is φ = 5625600.

The previous prime is 21802909. The next prime is 21802927. The reversal of 21802920 is 2920812.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21802927) 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, 790 + ... + 6650.

It is an arithmetic number, because the mean of its divisors is an integer number (1055160).

Almost surely, 2^21802920 is an apocalyptic number.

21802920 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 21802920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33765120).

21802920 is an abundant number, since it is smaller than the sum of its proper divisors (45727320).

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

21802920 is a wasteful number, since it uses less digits than its factorization.

21802920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5906 (or 5902 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 21802920 is about 4669.3596991451. The cubic root of 21802920 is about 279.3647161758.

It can be divided in two parts, 21802 and 920, that added together give a palindrome (22722).

The spelling of 21802920 in words is "twenty-one million, eight hundred two thousand, nine hundred twenty".