31981320 has 240 divisors, whose sum is σ = 124532460. Its totient is φ = 7112448.

The previous prime is 31981303. The next prime is 31981321. The reversal of 31981320 is 2318913.

It can be written as a sum of positive squares in 2 ways, for example, as 31203396 + 777924 = 5586^2 + 882^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (31981321) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 864342 + ... + 864378.

Almost surely, 2^31981320 is an apocalyptic number.

31981320 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 31981320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (62266230).

31981320 is an abundant number, since it is smaller than the sum of its proper divisors (92551140).

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

31981320 is a wasteful number, since it uses less digits than its factorization.

31981320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82 (or 54 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 31981320 is about 5655.2029141314. The cubic root of 31981320 is about 317.4184220115.

The spelling of 31981320 in words is "thirty-one million, nine hundred eighty-one thousand, three hundred twenty".