23921991 has 6 divisors (see below), whose sum is σ = 34554000. Its totient is φ = 15947988.

The previous prime is 23921977. The next prime is 23921993. The reversal of 23921991 is 19912932.

It is a happy number.

It is not a de Polignac number, because 23921991 - 2²¹ = 21824839 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (23921993) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1328991 + ... + 1329008.

It is an arithmetic number, because the mean of its divisors is an integer number (5759000).

Almost surely, 2^23921991 is an apocalyptic number.

23921991 is a deficient number, since it is larger than the sum of its proper divisors (10632009).

23921991 is a wasteful number, since it uses less digits than its factorization.

23921991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2658005 (or 2658002 counting only the distinct ones).

The product of its digits is 8748, while the sum is 36.

The square root of 23921991 is about 4891.0112451312. The cubic root of 23921991 is about 288.1370513794.

The spelling of 23921991 in words is "twenty-three million, nine hundred twenty-one thousand, nine hundred ninety-one".