90911591 has 4 divisors (see below), whose sum is σ = 90942792. Its totient is φ = 90880392.

The previous prime is 90911573. The next prime is 90911621. The reversal of 90911591 is 19511909.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19511909 = 47 ⋅415147.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-90911591 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 (90911501) 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, 10721 + ... + 17226.

It is an arithmetic number, because the mean of its divisors is an integer number (22735698).

Almost surely, 2^90911591 is an apocalyptic number.

90911591 is a deficient number, since it is larger than the sum of its proper divisors (31201).

90911591 is a wasteful number, since it uses less digits than its factorization.

90911591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31200.

The product of its (nonzero) digits is 3645, while the sum is 35.

The square root of 90911591 is about 9534.7569974279. The cubic root of 90911591 is about 449.6484348742.

The spelling of 90911591 in words is "ninety million, nine hundred eleven thousand, five hundred ninety-one".