31281228 has 120 divisors (see below), whose sum is σ = 91232064. Its totient is φ = 9266400.

The previous prime is 31281223. The next prime is 31281233. The reversal of 31281228 is 82218213.

It is an interprime number because it is at equal distance from previous prime (31281223) and next prime (31281233).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (31281223) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 238723 + ... + 238853.

Almost surely, 2^31281228 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 31281228, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45616032).

31281228 is an abundant number, since it is smaller than the sum of its proper divisors (59950836).

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

31281228 is a wasteful number, since it uses less digits than its factorization.

31281228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225 (or 214 counting only the distinct ones).

The product of its digits is 1536, while the sum is 27.

The square root of 31281228 is about 5592.9623635422. The cubic root of 31281228 is about 315.0851470500.

It can be divided in two parts, 3128 and 1228, that added together give a square (4356 = 66²).

The spelling of 31281228 in words is "thirty-one million, two hundred eighty-one thousand, two hundred twenty-eight".