990900 has 72 divisors (see below), whose sum is σ = 3194240. Its totient is φ = 263520.

The previous prime is 990893. The next prime is 990917. The reversal of 990900 is 9099.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2517 + ... + 2883.

2⁹⁹⁰⁹⁰⁰ is an apocalyptic number.

990900 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 990900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1597120).

990900 is an abundant number, since it is smaller than the sum of its proper divisors (2203340).

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

990900 is a wasteful number, since it uses less digits than its factorization.

990900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390 (or 377 counting only the distinct ones).

The product of its (nonzero) digits is 729, while the sum is 27.

The square root of 990900 is about 995.4396013822. The cubic root of 990900 is about 99.6957418755.

Adding to 990900 its reverse (9099), we get a palindrome (999999).

It can be divided in two parts, 9 and 90900, that added together give a palindrome (90909).

The spelling of 990900 in words is "nine hundred ninety thousand, nine hundred".