91878815 has 32 divisors (see below), whose sum is σ = 131535360. Its totient is φ = 60278400.

The previous prime is 91878803. The next prime is 91878847. The reversal of 91878815 is 51887819.

It is not a de Polignac number, because 91878815 - 2⁶ = 91878751 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91878815.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 132620 + ... + 133310.

It is an arithmetic number, because the mean of its divisors is an integer number (4110480).

Almost surely, 2^91878815 is an apocalyptic number.

91878815 is a deficient number, since it is larger than the sum of its proper divisors (39656545).

91878815 is a wasteful number, since it uses less digits than its factorization.

91878815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 863.

The product of its digits is 161280, while the sum is 47.

The square root of 91878815 is about 9585.3437601371. The cubic root of 91878815 is about 451.2374418126.

The spelling of 91878815 in words is "ninety-one million, eight hundred seventy-eight thousand, eight hundred fifteen".