31997240 has 64 divisors (see below), whose sum is σ = 79319520. Its totient is φ = 11616000.

The previous prime is 31997233. The next prime is 31997243. The reversal of 31997240 is 4279913.

It is a self number, because there is not a number n which added to its sum of digits gives 31997240.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31997243) 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, 52940 + ... + 53540.

Almost surely, 2^31997240 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31997240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39659760).

31997240 is an abundant number, since it is smaller than the sum of its proper divisors (47322280).

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

31997240 is a wasteful number, since it uses less digits than its factorization.

31997240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 645 (or 619 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 35.

The square root of 31997240 is about 5656.6102923924. The cubic root of 31997240 is about 317.4710825752.

The spelling of 31997240 in words is "thirty-one million, nine hundred ninety-seven thousand, two hundred forty".