90990 has 32 divisors (see below), whose sum is σ = 243360. Its totient is φ = 24192.

The previous prime is 90989. The next prime is 90997. The reversal of 90990 is 9909.

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 an Ulam number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90997) 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, 102 + ... + 438.

It is an arithmetic number, because the mean of its divisors is an integer number (7605).

2⁹⁰⁹⁹⁰ is an apocalyptic number.

90990 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 90990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121680).

90990 is an abundant number, since it is smaller than the sum of its proper divisors (152370).

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

90990 is a wasteful number, since it uses less digits than its factorization.

90990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 353 (or 347 counting only the distinct ones).

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

The square root of 90990 is about 301.6454872860. The cubic root of 90990 is about 44.9777667948.

Adding to 90990 its product of nonzero digits (729), we get a palindrome (91719).

It can be divided in two parts, 909 and 90, that multiplied together give a triangular number (81810 = T₄₀₄).

The spelling of 90990 in words is "ninety thousand, nine hundred ninety".