31213320 has 32 divisors (see below), whose sum is σ = 93640320. Its totient is φ = 8323520.

The previous prime is 31213289. The next prime is 31213321. The reversal of 31213320 is 2331213.

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

It is a nialpdrome in base 12.

It is a self number, because there is not a number n which added to its sum of digits gives 31213320.

It is not an unprimeable number, because it can be changed into a prime (31213321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 129936 + ... + 130175.

It is an arithmetic number, because the mean of its divisors is an integer number (2926260).

Almost surely, 2^31213320 is an apocalyptic number.

31213320 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

31213320 is an abundant number, since it is smaller than the sum of its proper divisors (62427000).

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

31213320 is a wasteful number, since it uses less digits than its factorization.

31213320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260125 (or 260121 counting only the distinct ones).

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

The square root of 31213320 is about 5586.8882215416. Note that the first 3 decimals coincide. The cubic root of 31213320 is about 314.8569771477.

Adding to 31213320 its reverse (2331213), we get a palindrome (33544533).

It can be divided in two parts, 3121 and 3320, that added together give a triangular number (6441 = T₁₁₃).

The spelling of 31213320 in words is "thirty-one million, two hundred thirteen thousand, three hundred twenty".