91686813 has 4 divisors (see below), whose sum is σ = 122249088. Its totient is φ = 61124540.

The previous prime is 91686811. The next prime is 91686823. The reversal of 91686813 is 31868619.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 91686813 - 2¹ = 91686811 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91686811) 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, 15281133 + ... + 15281138.

It is an arithmetic number, because the mean of its divisors is an integer number (30562272).

Almost surely, 2^91686813 is an apocalyptic number.

It is an amenable number.

91686813 is a deficient number, since it is larger than the sum of its proper divisors (30562275).

91686813 is a wasteful number, since it uses less digits than its factorization.

91686813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30562274.

The product of its digits is 62208, while the sum is 42.

The square root of 91686813 is about 9575.3231277070. The cubic root of 91686813 is about 450.9229009983.

The spelling of 91686813 in words is "ninety-one million, six hundred eighty-six thousand, eight hundred thirteen".