991090990 has 64 divisors (see below), whose sum is σ = 1936177344. Its totient is φ = 363870208.

The previous prime is 991090967. The next prime is 991091009. The reversal of 991090990 is 99090199.

It is a super-2 number, since 2×991090990² = 1964522700918360200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 991090990.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2855997 + ... + 2856343.

It is an arithmetic number, because the mean of its divisors is an integer number (30252771).

Almost surely, 2^991090990 is an apocalyptic number.

991090990 is a deficient number, since it is larger than the sum of its proper divisors (945086354).

991090990 is a wasteful number, since it uses less digits than its factorization.

991090990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 741.

The product of its (nonzero) digits is 59049, while the sum is 46.

The square root of 991090990 is about 31481.5976405264. The cubic root of 991090990 is about 997.0214671502.

The spelling of 991090990 in words is "nine hundred ninety-one million, ninety thousand, nine hundred ninety".