99131891 has 4 divisors (see below), whose sum is σ = 101549784. Its totient is φ = 96714000.

The previous prime is 99131887. The next prime is 99131897. The reversal of 99131891 is 19813199.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 99131891 - 2² = 99131887 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41), and also a Moran number because the ratio is a prime number: 2417851 = 99131891 / (9 + 9 + 1 + 3 + 1 + 8 + 9 + 1).

It is not an unprimeable number, because it can be changed into a prime (99131897) 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, 1208885 + ... + 1208966.

It is an arithmetic number, because the mean of its divisors is an integer number (25387446).

Almost surely, 2^99131891 is an apocalyptic number.

99131891 is a deficient number, since it is larger than the sum of its proper divisors (2417893).

99131891 is a wasteful number, since it uses less digits than its factorization.

99131891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2417892.

The product of its digits is 17496, while the sum is 41.

The square root of 99131891 is about 9956.4999372269. The cubic root of 99131891 is about 462.8118428687.

The spelling of 99131891 in words is "ninety-nine million, one hundred thirty-one thousand, eight hundred ninety-one".