91978887 has 64 divisors (see below), whose sum is σ = 166763520. Its totient is φ = 43545600.

The previous prime is 91978877. The next prime is 91978933. The reversal of 91978887 is 78887919.

It is not a de Polignac number, because 91978887 - 2¹⁰ = 91977863 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91978837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 327187 + ... + 327467.

It is an arithmetic number, because the mean of its divisors is an integer number (2605680).

Almost surely, 2^91978887 is an apocalyptic number.

91978887 is a deficient number, since it is larger than the sum of its proper divisors (74784633).

91978887 is a wasteful number, since it uses less digits than its factorization.

91978887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 424.

The product of its digits is 2032128, while the sum is 57.

The square root of 91978887 is about 9590.5623922688. The cubic root of 91978887 is about 451.4012077067.

The spelling of 91978887 in words is "ninety-one million, nine hundred seventy-eight thousand, eight hundred eighty-seven".