31133220 has 48 divisors (see below), whose sum is σ = 87823680. Its totient is φ = 8240256.

The previous prime is 31133213. The next prime is 31133231. The reversal of 31133220 is 2233113.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 31133220.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6474 + ... + 10206.

It is an arithmetic number, because the mean of its divisors is an integer number (1829660).

Almost surely, 2^31133220 is an apocalyptic number.

31133220 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31133220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43911840).

31133220 is an abundant number, since it is smaller than the sum of its proper divisors (56690460).

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

31133220 is a wasteful number, since it uses less digits than its factorization.

31133220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3884 (or 3882 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 15.

The square root of 31133220 is about 5579.7150464876. The cubic root of 31133220 is about 314.5874165028.

Adding to 31133220 its reverse (2233113), we get a palindrome (33366333).

The spelling of 31133220 in words is "thirty-one million, one hundred thirty-three thousand, two hundred twenty".