39999 has 8 divisors (see below), whose sum is σ = 54400. Its totient is φ = 26136.

The previous prime is 39989. The next prime is 40009. The reversal of 39999 is 99993.

It is a Cunningham number, because it is equal to 200²-1.

It is an interprime number because it is at equal distance from previous prime (39989) and next prime (40009).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 39999 - 2⁴ = 39983 is a prime.

It is a D-number.

It is a Duffinian number.

39999 is a modest number, since divided by 999 gives 39 as remainder.

It is a plaindrome in base 5 and base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39929) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 102 + ... + 300.

It is an arithmetic number, because the mean of its divisors is an integer number (6800).

2³⁹⁹⁹⁹ is an apocalyptic number.

39999 is a deficient number, since it is larger than the sum of its proper divisors (14401).

39999 is a wasteful number, since it uses less digits than its factorization.

39999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269.

The product of its digits is 19683, while the sum is 39.

The square root of 39999 is about 199.9974999844. The cubic root of 39999 is about 34.1992339352.

The spelling of 39999 in words is "thirty-nine thousand, nine hundred ninety-nine".