39990 has 32 divisors (see below), whose sum is σ = 101376. Its totient is φ = 10080.

The previous prime is 39989. The next prime is 40009. The reversal of 39990 is 9993.

39990 is nontrivially palindromic in base 4.

39990 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

39990 is an undulating number in base 6.

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, 909 + ... + 951.

It is an arithmetic number, because the mean of its divisors is an integer number (3168).

2³⁹⁹⁹⁰ is an apocalyptic number.

39990 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 39990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50688).

39990 is an abundant number, since it is smaller than the sum of its proper divisors (61386).

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

39990 is a wasteful number, since it uses less digits than its factorization.

39990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84.

The product of its (nonzero) digits is 2187, while the sum is 30.

The square root of 39990 is about 199.9749984373. The cubic root of 39990 is about 34.1966687361.

The spelling of 39990 in words is "thirty-nine thousand, nine hundred ninety".