9891990 has 32 divisors (see below), whose sum is σ = 26379360. Its totient is φ = 2637792.

The previous prime is 9891953. The next prime is 9891991. The reversal of 9891990 is 991989.

9891990 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9891991) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18049 + ... + 18588.

It is an arithmetic number, because the mean of its divisors is an integer number (824355).

Almost surely, 2^9891990 is an apocalyptic number.

9891990 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

9891990 is an abundant number, since it is smaller than the sum of its proper divisors (16487370).

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

9891990 is a wasteful number, since it uses less digits than its factorization.

9891990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36653 (or 36647 counting only the distinct ones).

The product of its (nonzero) digits is 52488, while the sum is 45.

The square root of 9891990 is about 3145.1534143822. The cubic root of 9891990 is about 214.6649911567.

The spelling of 9891990 in words is "nine million, eight hundred ninety-one thousand, nine hundred ninety".