21122320 has 20 divisors (see below), whose sum is σ = 49109580. Its totient is φ = 8448896.

The previous prime is 21122291. The next prime is 21122323. The reversal of 21122320 is 2322112.

It can be written as a sum of positive squares in 2 ways, for example, as 3549456 + 17572864 = 1884^2 + 4192^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 21122320.

It is not an unprimeable number, because it can be changed into a prime (21122323) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 131935 + ... + 132094.

It is an arithmetic number, because the mean of its divisors is an integer number (2455479).

Almost surely, 2^21122320 is an apocalyptic number.

21122320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21122320 is an abundant number, since it is smaller than the sum of its proper divisors (27987260).

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

21122320 is a wasteful number, since it uses less digits than its factorization.

21122320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264042 (or 264036 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21122320 is about 4595.9025229002. The cubic root of 21122320 is about 276.4270501568.

Adding to 21122320 its reverse (2322112), we get a palindrome (23444432).

The spelling of 21122320 in words is "twenty-one million, one hundred twenty-two thousand, three hundred twenty".