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BaseRepresentation
bin10011100000110
3111201000
42130012
5304430
6114130
741061
oct23406
914630
109990
117562
125946
134716
1438d8
152e60
hex2706

9990 has 32 divisors (see below), whose sum is σ = 27360. Its totient is φ = 2592.

The previous prime is 9973. The next prime is 10007. The reversal of 9990 is 999.

Subtracting from 9990 its product of nonzero digits (729), we obtain a cube (9261 = 213).

It can be divided in two parts, 9 and 990, that added together give a palindrome (999).

It is an interprime number because it is at equal distance from previous prime (9973) and next prime (10007).

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 a nialpdrome in base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 252 + ... + 288.

It is an arithmetic number, because the mean of its divisors is an integer number (855).

29990 is an apocalyptic number.

9990 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 9990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13680).

9990 is an abundant number, since it is smaller than the sum of its proper divisors (17370).

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

9990 is a wasteful number, since it uses less digits than its factorization.

9990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53 (or 47 counting only the distinct ones).

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

The square root of 9990 is about 99.9499874937. The cubic root of 9990 is about 21.5371630562.

The spelling of 9990 in words is "nine thousand, nine hundred ninety".