991000990 has 48 divisors (see below), whose sum is σ = 2077961904. Its totient is φ = 339292800.

The previous prime is 991000987. The next prime is 991000999. The reversal of 991000990 is 99000199.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991000999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 646525 + ... + 648055.

It is an arithmetic number, because the mean of its divisors is an integer number (43290873).

Almost surely, 2^991000990 is an apocalyptic number.

991000990 is an abundant number, since it is smaller than the sum of its proper divisors (1086960914).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991000990 is a wasteful number, since it uses less digits than its factorization.

991000990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2873 (or 2866 counting only the distinct ones).

The product of its (nonzero) digits is 6561, while the sum is 37.

The square root of 991000990 is about 31480.1682015837. The cubic root of 991000990 is about 996.9912867231.

The spelling of 991000990 in words is "nine hundred ninety-one million, nine hundred ninety", and thus it is an aban number.