91987923 has 4 divisors (see below), whose sum is σ = 122650568. Its totient is φ = 61325280.

The previous prime is 91987919. The next prime is 91987927. The reversal of 91987923 is 32978919.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32978919 = 3 ⋅10992973.

It is an interprime number because it is at equal distance from previous prime (91987919) and next prime (91987927).

It is not a de Polignac number, because 91987923 - 2² = 91987919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91987927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15331318 + ... + 15331323.

It is an arithmetic number, because the mean of its divisors is an integer number (30662642).

Almost surely, 2^91987923 is an apocalyptic number.

91987923 is a deficient number, since it is larger than the sum of its proper divisors (30662645).

91987923 is a wasteful number, since it uses less digits than its factorization.

91987923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30662644.

The product of its digits is 244944, while the sum is 48.

The square root of 91987923 is about 9591.0334688187. The cubic root of 91987923 is about 451.4159890979.

The spelling of 91987923 in words is "ninety-one million, nine hundred eighty-seven thousand, nine hundred twenty-three".