15990 has 32 divisors (see below), whose sum is σ = 42336. Its totient is φ = 3840.

The previous prime is 15973. The next prime is 15991. The reversal of 15990 is 9951.

It is a happy number.

It is a Curzon number.

It is a nialpdrome in base 7.

It is a self number, because there is not a number n which added to its sum of digits gives 15990.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 15990.

It is not an unprimeable number, because it can be changed into a prime (15991) 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, 370 + ... + 410.

It is an arithmetic number, because the mean of its divisors is an integer number (1323).

2¹⁵⁹⁹⁰ is an apocalyptic number.

15990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 15990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21168).

15990 is an abundant number, since it is smaller than the sum of its proper divisors (26346).

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

15990 is a wasteful number, since it uses less digits than its factorization.

15990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64.

The product of its (nonzero) digits is 405, while the sum is 24.

The square root of 15990 is about 126.4515717577. The cubic root of 15990 is about 25.1931702328.

The spelling of 15990 in words is "fifteen thousand, nine hundred ninety".