91638887 has 4 divisors (see below), whose sum is σ = 91702656. Its totient is φ = 91575120.

The previous prime is 91638863. The next prime is 91638901. The reversal of 91638887 is 78883619.

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 91638887 - 2¹⁶ = 91573351 is a prime.

It is a super-2 number, since 2×91638887² = 16795371221197538, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91638817) 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, 29678 + ... + 32619.

It is an arithmetic number, because the mean of its divisors is an integer number (22925664).

Almost surely, 2^91638887 is an apocalyptic number.

91638887 is a deficient number, since it is larger than the sum of its proper divisors (63769).

91638887 is a wasteful number, since it uses less digits than its factorization.

91638887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63768.

The product of its digits is 580608, while the sum is 50.

The square root of 91638887 is about 9572.8202218573. The cubic root of 91638887 is about 450.8443193689.

The spelling of 91638887 in words is "ninety-one million, six hundred thirty-eight thousand, eight hundred eighty-seven".