31128 has 16 divisors (see below), whose sum is σ = 77880. Its totient is φ = 10368.

The previous prime is 31123. The next prime is 31139. The reversal of 31128 is 82113.

It is a happy number.

It is a nude number because it is divisible by every one of its digits.

It is an Ulam number.

It is a plaindrome in base 13.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31121) 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, 625 + ... + 672.

2³¹¹²⁸ is an apocalyptic number.

It is an amenable number.

31128 is an abundant number, since it is smaller than the sum of its proper divisors (46752).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38940).

31128 is a wasteful number, since it uses less digits than its factorization.

31128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1306 (or 1302 counting only the distinct ones).

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

The square root of 31128 is about 176.4312897419. The cubic root of 31128 is about 31.4569833590.

Subtracting from 31128 its sum of digits (15), we obtain a palindrome (31113).

The spelling of 31128 in words is "thirty-one thousand, one hundred twenty-eight".