23201991 has 16 divisors (see below), whose sum is σ = 36396000. Its totient is φ = 14557824.

The previous prime is 23201989. The next prime is 23201999. The reversal of 23201991 is 19910232.

It is not a de Polignac number, because 23201991 - 2¹ = 23201989 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (23201999) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24816 + ... + 25733.

It is an arithmetic number, because the mean of its divisors is an integer number (2274750).

Almost surely, 2^23201991 is an apocalyptic number.

23201991 is a deficient number, since it is larger than the sum of its proper divisors (13194009).

23201991 is a wasteful number, since it uses less digits than its factorization.

23201991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50575 (or 50569 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 23201991 is about 4816.8445065208. The cubic root of 23201991 is about 285.2167879649.

The spelling of 23201991 in words is "twenty-three million, two hundred one thousand, nine hundred ninety-one".