23581991 has 4 divisors (see below), whose sum is σ = 23594184. Its totient is φ = 23569800.

The previous prime is 23581973. The next prime is 23582003. The reversal of 23581991 is 19918532.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 23581991 - 2⁶ = 23581927 is a prime.

It is a super-2 number, since 2×23581991² = 1112220599048162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (23581291) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2480 + ... + 7301.

It is an arithmetic number, because the mean of its divisors is an integer number (5898546).

Almost surely, 2^23581991 is an apocalyptic number.

23581991 is a deficient number, since it is larger than the sum of its proper divisors (12193).

23581991 is an equidigital number, since it uses as much as digits as its factorization.

23581991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12192.

The product of its digits is 19440, while the sum is 38.

The square root of 23581991 is about 4856.1292198623. The cubic root of 23581991 is about 286.7654483501.

The spelling of 23581991 in words is "twenty-three million, five hundred eighty-one thousand, nine hundred ninety-one".