90991090091 has 4 divisors (see below), whose sum is σ = 99263007384. Its totient is φ = 82719172800.

The previous prime is 90991090081. The next prime is 90991090103. The reversal of 90991090091 is 19009019909.

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

It is a de Polignac number, because none of the positive numbers 2^k-90991090091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (90991090051) 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, 4135958630 + ... + 4135958651.

It is an arithmetic number, because the mean of its divisors is an integer number (24815751846).

Almost surely, 2^90991090091 is an apocalyptic number.

90991090091 is a deficient number, since it is larger than the sum of its proper divisors (8271917293).

90991090091 is a wasteful number, since it uses less digits than its factorization.

90991090091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8271917292.

The product of its (nonzero) digits is 59049, while the sum is 47.

It can be divided in two parts, 909910 and 90091, that added together give a palindrome (1000001).

The spelling of 90991090091 in words is "ninety billion, nine hundred ninety-one million, ninety thousand, ninety-one".