91878691 has 4 divisors (see below), whose sum is σ = 92825992. Its totient is φ = 90931392.

The previous prime is 91878679. The next prime is 91878697. The reversal of 91878691 is 19687819.

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 91878691 - 2¹¹ = 91876643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91878697) 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, 473505 + ... + 473698.

It is an arithmetic number, because the mean of its divisors is an integer number (23206498).

Almost surely, 2^91878691 is an apocalyptic number.

91878691 is a deficient number, since it is larger than the sum of its proper divisors (947301).

91878691 is an equidigital number, since it uses as much as digits as its factorization.

91878691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 947300.

The product of its digits is 217728, while the sum is 49.

The square root of 91878691 is about 9585.3372919267. The cubic root of 91878691 is about 451.2372388152.

The spelling of 91878691 in words is "ninety-one million, eight hundred seventy-eight thousand, six hundred ninety-one".