999090 has 48 divisors (see below), whose sum is σ = 2754648. Its totient is φ = 250368.

The previous prime is 999083. The next prime is 999091. The reversal of 999090 is 90999.

It can be written as a sum of positive squares in 4 ways, for example, as 804609 + 194481 = 897^2 + 441^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (999091) by changing a digit.

999090 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1204 + ... + 1856.

2⁹⁹⁹⁰⁹⁰ is an apocalyptic number.

999090 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 999090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1377324).

999090 is an abundant number, since it is smaller than the sum of its proper divisors (1755558).

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

999090 is a wasteful number, since it uses less digits than its factorization.

999090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 683 (or 680 counting only the distinct ones).

The product of its (nonzero) digits is 6561, while the sum is 36.

The square root of 999090 is about 999.5448964404. The cubic root of 999090 is about 99.9696574609.

It can be divided in two parts, 9 and 99090, that added together give a palindrome (99099).

The spelling of 999090 in words is "nine hundred ninety-nine thousand, ninety".