31213312 has 72 divisors (see below), whose sum is σ = 68506704. Its totient is φ = 14106624.

The previous prime is 31213289. The next prime is 31213321. The reversal of 31213312 is 21331213.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 276168 + ... + 276280.

It is an arithmetic number, because the mean of its divisors is an integer number (951482).

Almost surely, 2^31213312 is an apocalyptic number.

31213312 is a gapful number since it is divisible by the number (32) 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 31213312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34253352).

31213312 is an abundant number, since it is smaller than the sum of its proper divisors (37293392).

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

31213312 is a wasteful number, since it uses less digits than its factorization.

31213312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225 (or 211 counting only the distinct ones).

The product of its digits is 108, while the sum is 16.

The square root of 31213312 is about 5586.8875055795. The cubic root of 31213312 is about 314.8569502483.

Adding to 31213312 its reverse (21331213), we get a palindrome (52544525).

The spelling of 31213312 in words is "thirty-one million, two hundred thirteen thousand, three hundred twelve".