31218 has 24 divisors (see below), whose sum is σ = 70224. Its totient is φ = 9240.

The previous prime is 31193. The next prime is 31219. The reversal of 31218 is 81213.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 31197 and 31206.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 31218.

It is not an unprimeable number, because it can be changed into a prime (31219) by changing a digit.

31218 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 11 ways as a sum of consecutive naturals, for example, 705 + ... + 747.

It is an arithmetic number, because the mean of its divisors is an integer number (2926).

2³¹²¹⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31218, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35112).

31218 is an abundant number, since it is smaller than the sum of its proper divisors (39006).

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

31218 is a wasteful number, since it uses less digits than its factorization.

31218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70 (or 59 counting only the distinct ones).

The product of its digits is 48, while the sum is 15.

The square root of 31218 is about 176.6861624463. The cubic root of 31218 is about 31.4872712492.

It can be divided in two parts, 3 and 1218, that added together give a palindrome (1221).

The spelling of 31218 in words is "thirty-one thousand, two hundred eighteen".