31556 has 24 divisors (see below), whose sum is σ = 67200. Its totient is φ = 12936.

The previous prime is 31547. The next prime is 31567. The reversal of 31556 is 65513.

It is a super-2 number, since 2×31556² = 1991562272, which contains 22 as substring.

It is an Ulam number.

It is a nialpdrome in base 14.

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 31556.

It is an unprimeable number.

31556 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1361 + ... + 1383.

It is an arithmetic number, because the mean of its divisors is an integer number (2800).

2³¹⁵⁵⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33600).

31556 is an abundant number, since it is smaller than the sum of its proper divisors (35644).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31556 is a wasteful number, since it uses less digits than its factorization.

31556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48 (or 32 counting only the distinct ones).

The product of its digits is 450, while the sum is 20.

The square root of 31556 is about 177.6400855663. The cubic root of 31556 is about 31.6005020483.

The spelling of 31556 in words is "thirty-one thousand, five hundred fifty-six".