90190091 has 4 divisors (see below), whose sum is σ = 90210552. Its totient is φ = 90169632.

The previous prime is 90190069. The next prime is 90190099. The reversal of 90190091 is 19009109.

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

It is a cyclic number.

It is not a de Polignac number, because 90190091 - 2¹⁸ = 89927947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (90190099) 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, 590 + ... + 13443.

It is an arithmetic number, because the mean of its divisors is an integer number (22552638).

Almost surely, 2^90190091 is an apocalyptic number.

90190091 is a deficient number, since it is larger than the sum of its proper divisors (20461).

90190091 is a wasteful number, since it uses less digits than its factorization.

90190091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20460.

The product of its (nonzero) digits is 729, while the sum is 29.

The square root of 90190091 is about 9496.8463712961. The cubic root of 90190091 is about 448.4557619364.

The spelling of 90190091 in words is "ninety million, one hundred ninety thousand, ninety-one".