31231320 has 64 divisors (see below), whose sum is σ = 94180320. Its totient is φ = 8285184.

The previous prime is 31231303. The next prime is 31231327. The reversal of 31231320 is 2313213.

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

It is a self number, because there is not a number n which added to its sum of digits gives 31231320.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31231327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27402 + ... + 28518.

Almost surely, 2^31231320 is an apocalyptic number.

31231320 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 31231320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47090160).

31231320 is an abundant number, since it is smaller than the sum of its proper divisors (62949000).

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

31231320 is a wasteful number, since it uses less digits than its factorization.

31231320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1364 (or 1360 counting only the distinct ones).

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

The square root of 31231320 is about 5588.4989039992. The cubic root of 31231320 is about 314.9174890970.

Adding to 31231320 its reverse (2313213), we get a palindrome (33544533).

The spelling of 31231320 in words is "thirty-one million, two hundred thirty-one thousand, three hundred twenty".