39 has 4 divisors (see below), whose sum is σ = 56.
Its totient is φ = 24.
The previous prime is 37. The next prime is 41. The reversal of 39 is 93.
39 is nontrivially palindromic in base 12.
39 is an esthetic number in base 7 and base 9, because in such bases it adjacent digits differ by 1.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93 = 3 ⋅31.
It is an interprime number because it is at equal distance from previous prime (37) and next prime (41).
It is not a de Polignac number, because 39 - 21 = 37 is a prime.
It is an iccanobiF number.
It is a D-number.
It is a Duffinian number.
39 is a modest number, since divided by 9 gives 3 as remainder.
It is the 13-th Perrin number.
39 is a nontrivial repdigit in base 12.
It is a plaindrome in base 5, base 8, base 10, base 11, base 12, base 14, base 15 and base 16.
It is a nialpdrome in base 3, base 7, base 9, base 12 and base 13.
It is a zygodrome in base 12.
It is a congruent number.
It is a panconsummate number.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4 + ... + 9.
It is an arithmetic number, because the mean of its divisors is an integer number (14).
39 is a deficient number, since it is larger than the sum of its proper divisors (17).
39 is a wasteful number, since it uses less digits than its factorization.
39 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 16.
The product of its digits is 27, while the sum is 12.
The square root of 39 is about 6.2449979984.
The cubic root of 39 is about 3.3912114430.
The spelling of 39 in words is "thirty-nine", and is thus an aban number, an oban number, and an uban number.