990091 has 4 divisors (see below), whose sum is σ = 1006384. Its totient is φ = 973800.

The previous prime is 990053. The next prime is 990137. The reversal of 990091 is 190099.

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 990091 - 2⁹ = 989579 is a prime.

It is a Duffinian number.

990091 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (990001) 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, 8055 + ... + 8176.

It is an arithmetic number, because the mean of its divisors is an integer number (251596).

2⁹⁹⁰⁰⁹¹ is an apocalyptic number.

990091 is a deficient number, since it is larger than the sum of its proper divisors (16293).

990091 is a wasteful number, since it uses less digits than its factorization.

990091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16292.

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

The square root of 990091 is about 995.0331652764. The cubic root of 990091 is about 99.6686029733.

It can be divided in two parts, 9 and 90091, that added together give a triangular number (90100 = T₄₂₄).

The spelling of 990091 in words is "nine hundred ninety thousand, ninety-one".