91139913 has 24 divisors (see below), whose sum is σ = 135095688. Its totient is φ = 59185152.

The previous prime is 91139887. The next prime is 91139929. The reversal of 91139913 is 31993119.

It can be written as a sum of positive squares in 4 ways, for example, as 8838729 + 82301184 = 2973^2 + 9072^2 .

It is not a de Polignac number, because 91139913 - 2⁶ = 91139849 is a prime.

It is a nude number because it is divisible by every one of its digits.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (91139933) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 74281 + ... + 75497.

It is an arithmetic number, because the mean of its divisors is an integer number (5628987).

Almost surely, 2^91139913 is an apocalyptic number.

It is an amenable number.

91139913 is a deficient number, since it is larger than the sum of its proper divisors (43955775).

91139913 is a wasteful number, since it uses less digits than its factorization.

91139913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1433 (or 1430 counting only the distinct ones).

The product of its digits is 6561, while the sum is 36.

The square root of 91139913 is about 9546.7226313537. The cubic root of 91139913 is about 450.0245468091.

The spelling of 91139913 in words is "ninety-one million, one hundred thirty-nine thousand, nine hundred thirteen".