31639 has 4 divisors (see below), whose sum is σ = 32760.
Its totient is φ = 30520.
The previous prime is 31627. The next prime is 31643. The reversal of 31639 is 93613.
It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is not a de Polignac number, because 31639 - 25 = 31607 is a prime.
It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.
It is a Duffinian number.
31639 is a lucky number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (31649) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (11) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 517 + ... + 574.
It is an arithmetic number, because the mean of its divisors is an integer number (8190).
231639 is an apocalyptic number.
31639 is a deficient number, since it is larger than the sum of its proper divisors (1121).
31639 is a wasteful number, since it uses less digits than its factorization.
31639 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 1120.
The product of its digits is 486, while the sum is 22.
The square root of 31639 is about 177.8735505914.
The cubic root of 31639 is about 31.6281834766.
The spelling of 31639 in words is "thirty-one thousand, six hundred thirty-nine".