900090 has 48 divisors (see below), whose sum is σ = 2389608. Its totient is φ = 235008.

The previous prime is 900089. The next prime is 900091. The reversal of 900090 is 90009.

It is an interprime number because it is at equal distance from previous prime (900089) and next prime (900091).

It can be written as a sum of positive squares in 4 ways, for example, as 772641 + 127449 = 879^2 + 357^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

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

It is not an unprimeable number, because it can be changed into a prime (900091) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6502 + ... + 6638.

2⁹⁰⁰⁰⁹⁰ is an apocalyptic number.

900090 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 900090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1194804).

900090 is an abundant number, since it is smaller than the sum of its proper divisors (1489518).

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

900090 is a wasteful number, since it uses less digits than its factorization.

900090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223 (or 220 counting only the distinct ones).

The product of its (nonzero) digits is 81, while the sum is 18.

The square root of 900090 is about 948.7307310296. The cubic root of 900090 is about 96.5521566512.

900090 divided by its sum of digits (18) gives a palindrome (50005).

Subtracting from 900090 its product of nonzero digits (81), we obtain a palindrome (900009).

Adding to 900090 its reverse (90009), we get a palindrome (990099).

It can be divided in two parts, 9000 and 90, that multiplied together give a 4-th power (810000 = 30⁴).

The spelling of 900090 in words is "nine hundred thousand, ninety".