23979821 has 2 divisors, whose sum is σ = 23979822. Its totient is φ = 23979820.

The previous prime is 23979817. The next prime is 23979827. The reversal of 23979821 is 12897932.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18826921 + 5152900 = 4339^2 + 2270^2 .

It is a cyclic number.

It is not a de Polignac number, because 23979821 - 2² = 23979817 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (23979827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11989910 + 11989911.

It is an arithmetic number, because the mean of its divisors is an integer number (11989911).

Almost surely, 2^23979821 is an apocalyptic number.

It is an amenable number.

23979821 is a deficient number, since it is larger than the sum of its proper divisors (1).

23979821 is an equidigital number, since it uses as much as digits as its factorization.

23979821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 41.

The square root of 23979821 is about 4896.9195419161. The cubic root of 23979821 is about 288.3690492991.

The spelling of 23979821 in words is "twenty-three million, nine hundred seventy-nine thousand, eight hundred twenty-one".