31239972 has 48 divisors (see below), whose sum is σ = 81614400. Its totient is φ = 10333440.

The previous prime is 31239961. The next prime is 31239977. The reversal of 31239972 is 27993213.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (31239977) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13972 + ... + 16052.

It is an arithmetic number, because the mean of its divisors is an integer number (1700300).

Almost surely, 2^31239972 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 31239972, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40807200).

31239972 is an abundant number, since it is smaller than the sum of its proper divisors (50374428).

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

31239972 is a wasteful number, since it uses less digits than its factorization.

31239972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2233 (or 2225 counting only the distinct ones).

The product of its digits is 20412, while the sum is 36.

The square root of 31239972 is about 5589.2729401954. The cubic root of 31239972 is about 314.9465669004.

The spelling of 31239972 in words is "thirty-one million, two hundred thirty-nine thousand, nine hundred seventy-two".