31031220 has 48 divisors (see below), whose sum is σ = 94788288. Its totient is φ = 7522560.

The previous prime is 31031201. The next prime is 31031257. The reversal of 31031220 is 2213013.

It is a happy number.

It is a super-2 number, since 2×31031220² = 1925873229376800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 31031196 and 31031205.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22849 + ... + 24168.

It is an arithmetic number, because the mean of its divisors is an integer number (1974756).

Almost surely, 2^31031220 is an apocalyptic number.

31031220 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

31031220 is an abundant number, since it is smaller than the sum of its proper divisors (63757068).

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

31031220 is a wasteful number, since it uses less digits than its factorization.

31031220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47040 (or 47038 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 31031220 is about 5570.5672960660. The cubic root of 31031220 is about 314.2434856682.

Adding to 31031220 its reverse (2213013), we get a palindrome (33244233).

The spelling of 31031220 in words is "thirty-one million, thirty-one thousand, two hundred twenty".