31109220 has 36 divisors (see below), whose sum is σ = 94365180. Its totient is φ = 8295744.

The previous prime is 31109209. The next prime is 31109233. The reversal of 31109220 is 2290113.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 4235364 + 26873856 = 2058^2 + 5184^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 31109193 and 31109202.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 86235 + ... + 86594.

It is an arithmetic number, because the mean of its divisors is an integer number (2621255).

Almost surely, 2^31109220 is an apocalyptic number.

31109220 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

31109220 is an abundant number, since it is smaller than the sum of its proper divisors (63255960).

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

31109220 is a wasteful number, since it uses less digits than its factorization.

31109220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172844 (or 172839 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 31109220 is about 5577.5639843932. The cubic root of 31109220 is about 314.5065592609.

Adding to 31109220 its reverse (2290113), we get a palindrome (33399333).

It can be divided in two parts, 31109 and 220, that added together give a square (31329 = 177²).

The spelling of 31109220 in words is "thirty-one million, one hundred nine thousand, two hundred twenty".