23720561 has 2 divisors, whose sum is σ = 23720562. Its totient is φ = 23720560.

The previous prime is 23720533. The next prime is 23720597. The reversal of 23720561 is 16502732.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22657600 + 1062961 = 4760^2 + 1031^2 .

It is a cyclic number.

It is not a de Polignac number, because 23720561 - 2⁶ = 23720497 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 23720561.

It is not a weakly prime, because it can be changed into another prime (23720261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11860280 + 11860281.

It is an arithmetic number, because the mean of its divisors is an integer number (11860281).

Almost surely, 2^23720561 is an apocalyptic number.

It is an amenable number.

23720561 is a deficient number, since it is larger than the sum of its proper divisors (1).

23720561 is an equidigital number, since it uses as much as digits as its factorization.

23720561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 23720561 is about 4870.3758581859. The cubic root of 23720561 is about 287.3260386796.

The spelling of 23720561 in words is "twenty-three million, seven hundred twenty thousand, five hundred sixty-one".