900990 has 64 divisors (see below), whose sum is σ = 2488320. Its totient is φ = 231840.

The previous prime is 900973. The next prime is 900997. The reversal of 900990 is 99009.

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.

900990 is a modest number, since divided by 990 gives 90 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (900997) by changing a digit.

900990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12655 + ... + 12725.

It is an arithmetic number, because the mean of its divisors is an integer number (38880).

2⁹⁰⁰⁹⁹⁰ is an apocalyptic number.

900990 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 900990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1244160).

900990 is an abundant number, since it is smaller than the sum of its proper divisors (1587330).

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

900990 is a wasteful number, since it uses less digits than its factorization.

900990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134 (or 128 counting only the distinct ones).

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

The square root of 900990 is about 949.2049304550. The cubic root of 900990 is about 96.5843267655.

Adding to 900990 its reverse (99009), we get a palindrome (999999).

The spelling of 900990 in words is "nine hundred thousand, nine hundred ninety".