39921 has 8 divisors (see below), whose sum is σ = 60864. Its totient is φ = 22800.

The previous prime is 39901. The next prime is 39929. The reversal of 39921 is 12993.

It is a happy number.

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

It is not a de Polignac number, because 39921 - 2⁶ = 39857 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 39891 and 39900.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 39921.

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, 930 + ... + 971.

It is an arithmetic number, because the mean of its divisors is an integer number (7608).

2³⁹⁹²¹ is an apocalyptic number.

It is an amenable number.

39921 is a deficient number, since it is larger than the sum of its proper divisors (20943).

39921 is a wasteful number, since it uses less digits than its factorization.

39921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1911.

The product of its digits is 486, while the sum is 24.

The square root of 39921 is about 199.8024023880. The cubic root of 39921 is about 34.1769894118.

It can be divided in two parts, 3992 and 1, that added together give a palindrome (3993).

The spelling of 39921 in words is "thirty-nine thousand, nine hundred twenty-one".