91990013 has 4 divisors (see below), whose sum is σ = 93498108. Its totient is φ = 90481920.

The previous prime is 91990007. The next prime is 91990081. The reversal of 91990013 is 31009919.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31009919 = 19 ⋅1632101.

It can be written as a sum of positive squares in 2 ways, for example, as 53772889 + 38217124 = 7333^2 + 6182^2 .

It is a cyclic number.

It is not a de Polignac number, because 91990013 - 2²⁰ = 90941437 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 (91992013) 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, 753956 + ... + 754077.

It is an arithmetic number, because the mean of its divisors is an integer number (23374527).

Almost surely, 2^91990013 is an apocalyptic number.

It is an amenable number.

91990013 is a deficient number, since it is larger than the sum of its proper divisors (1508095).

91990013 is a wasteful number, since it uses less digits than its factorization.

91990013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1508094.

The product of its (nonzero) digits is 2187, while the sum is 32.

The square root of 91990013 is about 9591.1424241328. The cubic root of 91990013 is about 451.4194078520.

The spelling of 91990013 in words is "ninety-one million, nine hundred ninety thousand, thirteen".