31304220 has 96 divisors (see below), whose sum is σ = 91929600. Its totient is φ = 7951104.

The previous prime is 31304201. The next prime is 31304227. The reversal of 31304220 is 2240313.

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 31304220.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31304227) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 130861 + ... + 131099.

It is an arithmetic number, because the mean of its divisors is an integer number (957600).

Almost surely, 2^31304220 is an apocalyptic number.

31304220 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 31304220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45964800).

31304220 is an abundant number, since it is smaller than the sum of its proper divisors (60625380).

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

31304220 is a wasteful number, since it uses less digits than its factorization.

31304220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 347 (or 345 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 31304220 is about 5595.0174262463. The cubic root of 31304220 is about 315.1623250039.

Adding to 31304220 its reverse (2240313), we get a palindrome (33544533).

The spelling of 31304220 in words is "thirty-one million, three hundred four thousand, two hundred twenty".