23661981 has 24 divisors (see below), whose sum is σ = 40120704. Its totient is φ = 13154400.

The previous prime is 23661947. The next prime is 23661983. The reversal of 23661981 is 18916632.

23661981 is a `hidden beast` number, since 2 + 36 + 619 + 8 + 1 = 666.

It is not a de Polignac number, because 23661981 - 2¹⁴ = 23645597 is a prime.

It is a super-2 number, since 2×23661981² = 1119778689688722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (23661983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2745 + ... + 7406.

It is an arithmetic number, because the mean of its divisors is an integer number (1671696).

Almost surely, 2^23661981 is an apocalyptic number.

23661981 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

23661981 is a deficient number, since it is larger than the sum of its proper divisors (16458723).

23661981 is a wasteful number, since it uses less digits than its factorization.

23661981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10201 (or 10198 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 23661981 is about 4864.3582310517. The cubic root of 23661981 is about 287.0893181110.

It can be divided in two parts, 23661 and 981, that added together give a palindrome (24642).

The spelling of 23661981 in words is "twenty-three million, six hundred sixty-one thousand, nine hundred eighty-one".