99990 has 48 divisors (see below), whose sum is σ = 286416. Its totient is φ = 24000.

The previous prime is 99989. The next prime is 99991. The reversal of 99990 is 9999.

It is an interprime number because it is at equal distance from previous prime (99989) and next prime (99991).

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99991) 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, 940 + ... + 1040.

It is an arithmetic number, because the mean of its divisors is an integer number (5967).

2⁹⁹⁹⁹⁰ is an apocalyptic number.

99990 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 99990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (143208).

99990 is an abundant number, since it is smaller than the sum of its proper divisors (186426).

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

99990 is a wasteful number, since it uses less digits than its factorization.

99990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125 (or 122 counting only the distinct ones).

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

The square root of 99990 is about 316.2119542332. The cubic root of 99990 is about 46.4143410883.

It can be divided in two parts, 999 and 90, that added together give a square (1089 = 33²).

The spelling of 99990 in words is "ninety-nine thousand, nine hundred ninety".