91815133 has 4 divisors (see below), whose sum is σ = 93547548. Its totient is φ = 90082720.

The previous prime is 91815091. The next prime is 91815137. The reversal of 91815133 is 33151819.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 33151819 = 17 ⋅1950107.

It can be written as a sum of positive squares in 2 ways, for example, as 82682649 + 9132484 = 9093^2 + 3022^2 .

It is a cyclic number.

It is not a de Polignac number, because 91815133 - 2²⁵ = 58260701 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 91815095 and 91815104.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91815137) 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, 866128 + ... + 866233.

It is an arithmetic number, because the mean of its divisors is an integer number (23386887).

Almost surely, 2^91815133 is an apocalyptic number.

It is an amenable number.

91815133 is a deficient number, since it is larger than the sum of its proper divisors (1732415).

91815133 is a wasteful number, since it uses less digits than its factorization.

91815133 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1732414.

The product of its digits is 3240, while the sum is 31.

The square root of 91815133 is about 9582.0213420760. The cubic root of 91815133 is about 451.1331655282.

The spelling of 91815133 in words is "ninety-one million, eight hundred fifteen thousand, one hundred thirty-three".