22721 has 2 divisors, whose sum is σ = 22722. Its totient is φ = 22720.

The previous prime is 22717. The next prime is 22727. The reversal of 22721 is 12722.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18496 + 4225 = 136^2 + 65^2 .

It is a cyclic number.

It is not a de Polignac number, because 22721 - 2² = 22717 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 22696 and 22705.

It is not a weakly prime, because it can be changed into another prime (22727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11360 + 11361.

It is an arithmetic number, because the mean of its divisors is an integer number (11361).

2²²⁷²¹ is an apocalyptic number.

It is an amenable number.

22721 is a deficient number, since it is larger than the sum of its proper divisors (1).

22721 is an equidigital number, since it uses as much as digits as its factorization.

22721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56, while the sum is 14.

The square root of 22721 is about 150.7348665704. The cubic root of 22721 is about 28.3232105322.

Subtracting from 22721 its reverse (12722), we obtain a palindrome (9999).

The spelling of 22721 in words is "twenty-two thousand, seven hundred twenty-one", and thus it is an iban number.