23639681 has 4 divisors (see below), whose sum is σ = 25458132. Its totient is φ = 21821232.

The previous prime is 23639659. The next prime is 23639683. The reversal of 23639681 is 18693632.

23639681 = 941² + 942² + ... + 966².

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 982081 + 22657600 = 991^2 + 4760^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-23639681 is a prime.

It is a super-2 number, since 2×23639681² = 1117669035563522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (23639683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 909206 + ... + 909231.

It is an arithmetic number, because the mean of its divisors is an integer number (6364533).

Almost surely, 2^23639681 is an apocalyptic number.

It is an amenable number.

23639681 is a deficient number, since it is larger than the sum of its proper divisors (1818451).

23639681 is a wasteful number, since it uses less digits than its factorization.

23639681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1818450.

The product of its digits is 46656, while the sum is 38.

The square root of 23639681 is about 4862.0655075801. The cubic root of 23639681 is about 286.9991016009. Note that the first 3 decimals are identical.

The spelling of 23639681 in words is "twenty-three million, six hundred thirty-nine thousand, six hundred eighty-one".