91090009 has 4 divisors (see below), whose sum is σ = 95884240. Its totient is φ = 86295780.

The previous prime is 91089949. The next prime is 91090037. The reversal of 91090009 is 90009019.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91090009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91090049) 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, 2397087 + ... + 2397124.

It is an arithmetic number, because the mean of its divisors is an integer number (23971060).

Almost surely, 2^91090009 is an apocalyptic number.

It is an amenable number.

91090009 is a deficient number, since it is larger than the sum of its proper divisors (4794231).

91090009 is a wasteful number, since it uses less digits than its factorization.

91090009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4794230.

The product of its (nonzero) digits is 729, while the sum is 28.

The square root of 91090009 is about 9544.1086016453. The cubic root of 91090009 is about 449.9423942721.

The spelling of 91090009 in words is "ninety-one million, ninety thousand, nine".