91321687 has 4 divisors (see below), whose sum is σ = 91380960. Its totient is φ = 91262416.

The previous prime is 91321679. The next prime is 91321721. The reversal of 91321687 is 78612319.

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 91321687 - 2³ = 91321679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91321627) 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, 27262 + ... + 30427.

It is an arithmetic number, because the mean of its divisors is an integer number (22845240).

Almost surely, 2^91321687 is an apocalyptic number.

91321687 is a deficient number, since it is larger than the sum of its proper divisors (59273).

91321687 is a wasteful number, since it uses less digits than its factorization.

91321687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59272.

The product of its digits is 18144, while the sum is 37.

The square root of 91321687 is about 9556.2381196787. The cubic root of 91321687 is about 450.3235319468.

The spelling of 91321687 in words is "ninety-one million, three hundred twenty-one thousand, six hundred eighty-seven".