91800013 has 4 divisors (see below), whose sum is σ = 91885248. Its totient is φ = 91714780.

The previous prime is 91799999. The next prime is 91800019. The reversal of 91800013 is 31000819.

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, and also an emirpimes, since its reverse is a distinct semiprime: 31000819 = 1499 ⋅20681.

It is a cyclic number.

It is not a de Polignac number, because 91800013 - 2²¹ = 89702861 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 (91800019) 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, 40981 + ... + 43162.

It is an arithmetic number, because the mean of its divisors is an integer number (22971312).

Almost surely, 2^91800013 is an apocalyptic number.

It is an amenable number.

91800013 is a deficient number, since it is larger than the sum of its proper divisors (85235).

91800013 is a wasteful number, since it uses less digits than its factorization.

91800013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85234.

The product of its (nonzero) digits is 216, while the sum is 22.

The square root of 91800013 is about 9581.2323320124. The cubic root of 91800013 is about 451.1084001556.

The spelling of 91800013 in words is "ninety-one million, eight hundred thousand, thirteen".