91097999 has 4 divisors (see below), whose sum is σ = 91643664. Its totient is φ = 90552336.

The previous prime is 91097987. The next prime is 91098031. The reversal of 91097999 is 99979019.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91097999 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 91097999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91097969) 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, 272582 + ... + 272915.

It is an arithmetic number, because the mean of its divisors is an integer number (22910916).

Almost surely, 2^91097999 is an apocalyptic number.

91097999 is a deficient number, since it is larger than the sum of its proper divisors (545665).

91097999 is a wasteful number, since it uses less digits than its factorization.

91097999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 545664.

The product of its (nonzero) digits is 413343, while the sum is 53.

The square root of 91097999 is about 9544.5271752979. The cubic root of 91097999 is about 449.9555495188.

The spelling of 91097999 in words is "ninety-one million, ninety-seven thousand, nine hundred ninety-nine".