22531721 has 2 divisors, whose sum is σ = 22531722. Its totient is φ = 22531720.

The previous prime is 22531711. The next prime is 22531723. The reversal of 22531721 is 12713522.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11806096 + 10725625 = 3436^2 + 3275^2 .

It is a cyclic number.

It is not a de Polignac number, because 22531721 - 2⁶ = 22531657 is a prime.

It is a Sophie Germain prime.

Together with 22531723, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (22531723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11265860 + 11265861.

It is an arithmetic number, because the mean of its divisors is an integer number (11265861).

Almost surely, 2^22531721 is an apocalyptic number.

It is an amenable number.

22531721 is a deficient number, since it is larger than the sum of its proper divisors (1).

22531721 is an equidigital number, since it uses as much as digits as its factorization.

22531721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 840, while the sum is 23.

The square root of 22531721 is about 4746.7589995701. The cubic root of 22531721 is about 282.4434157169.

The spelling of 22531721 in words is "twenty-two million, five hundred thirty-one thousand, seven hundred twenty-one".