23505721 has 2 divisors, whose sum is σ = 23505722. Its totient is φ = 23505720.

The previous prime is 23505709. The next prime is 23505737. The reversal of 23505721 is 12750532.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23145721 + 360000 = 4811^2 + 600^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-23505721 is a prime.

It is not a weakly prime, because it can be changed into another prime (23505791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11752860 + 11752861.

It is an arithmetic number, because the mean of its divisors is an integer number (11752861).

Almost surely, 2^23505721 is an apocalyptic number.

It is an amenable number.

23505721 is a deficient number, since it is larger than the sum of its proper divisors (1).

23505721 is an equidigital number, since it uses as much as digits as its factorization.

23505721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 23505721 is about 4848.2698976026. The cubic root of 23505721 is about 286.4559576233.

The spelling of 23505721 in words is "twenty-three million, five hundred five thousand, seven hundred twenty-one".