31316220 has 120 divisors (see below), whose sum is σ = 105868224. Its totient is φ = 7703424.

The previous prime is 31316213. The next prime is 31316249. The reversal of 31316220 is 2261313.

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 = 31316193 and 31316202.

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 39 ways as a sum of consecutive naturals, for example, 20317 + ... + 21803.

Almost surely, 2^31316220 is an apocalyptic number.

31316220 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 31316220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (52934112).

31316220 is an abundant number, since it is smaller than the sum of its proper divisors (74552004).

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

31316220 is a wasteful number, since it uses less digits than its factorization.

31316220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1521 (or 1510 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 31316220 is about 5596.0897062145. The cubic root of 31316220 is about 315.2025907652.

Adding to 31316220 its reverse (2261313), we get a palindrome (33577533).

The spelling of 31316220 in words is "thirty-one million, three hundred sixteen thousand, two hundred twenty".