23665721 has 2 divisors, whose sum is σ = 23665722. Its totient is φ = 23665720.

The previous prime is 23665699. The next prime is 23665727. The reversal of 23665721 is 12756632.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23658496 + 7225 = 4864^2 + 85^2 .

It is a cyclic number.

It is not a de Polignac number, because 23665721 - 2⁶ = 23665657 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (23665727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11832860 + 11832861.

It is an arithmetic number, because the mean of its divisors is an integer number (11832861).

Almost surely, 2^23665721 is an apocalyptic number.

It is an amenable number.

23665721 is a deficient number, since it is larger than the sum of its proper divisors (1).

23665721 is an equidigital number, since it uses as much as digits as its factorization.

23665721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15120, while the sum is 32.

The square root of 23665721 is about 4864.7426447861. The cubic root of 23665721 is about 287.1044430420.

The spelling of 23665721 in words is "twenty-three million, six hundred sixty-five thousand, seven hundred twenty-one".