21022320 has 80 divisors (see below), whose sum is σ = 71102592. Its totient is φ = 5095680.

The previous prime is 21022279. The next prime is 21022357. The reversal of 21022320 is 2322012.

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 (12).

It is a junction number, because it is equal to n+sod(n) for n = 21022296 and 21022305.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1342 + ... + 6621.

Almost surely, 2^21022320 is an apocalyptic number.

21022320 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 21022320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35551296).

21022320 is an abundant number, since it is smaller than the sum of its proper divisors (50080272).

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

21022320 is a wasteful number, since it uses less digits than its factorization.

21022320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7990 (or 7984 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 21022320 is about 4585.0103598574. The cubic root of 21022320 is about 275.9901277712.

Adding to 21022320 its reverse (2322012), we get a palindrome (23344332).

The spelling of 21022320 in words is "twenty-one million, twenty-two thousand, three hundred twenty".