31917 has 4 divisors (see below), whose sum is σ = 42560. Its totient is φ = 21276.

The previous prime is 31907. The next prime is 31957. The reversal of 31917 is 71913.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 71913 = 3 ⋅23971.

It is not a de Polignac number, because 31917 - 2¹⁰ = 30893 is a prime.

It is a D-number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31893 and 31902.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 31917.

It is not an unprimeable number, because it can be changed into a prime (31907) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5317 + ... + 5322.

It is an arithmetic number, because the mean of its divisors is an integer number (10640).

2³¹⁹¹⁷ is an apocalyptic number.

It is an amenable number.

31917 is a deficient number, since it is larger than the sum of its proper divisors (10643).

31917 is a wasteful number, since it uses less digits than its factorization.

31917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10642.

The product of its digits is 189, while the sum is 21.

The square root of 31917 is about 178.6532955196. The cubic root of 31917 is about 31.7205484635.

The spelling of 31917 in words is "thirty-one thousand, nine hundred seventeen".