31971940 has 96 divisors (see below), whose sum is σ = 90203904. Its totient is φ = 9192960.

The previous prime is 31971911. The next prime is 31971941. The reversal of 31971940 is 4917913.

It is a junction number, because it is equal to n+sod(n) for n = 31971896 and 31971905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31971941) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19222 + ... + 20818.

It is an arithmetic number, because the mean of its divisors is an integer number (939624).

Almost surely, 2^31971940 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 31971940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45101952).

31971940 is an abundant number, since it is smaller than the sum of its proper divisors (58231964).

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

31971940 is a wasteful number, since it uses less digits than its factorization.

31971940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1637 (or 1635 counting only the distinct ones).

The product of its (nonzero) digits is 6804, while the sum is 34.

The square root of 31971940 is about 5654.3735285175. The cubic root of 31971940 is about 317.3873864369.

The spelling of 31971940 in words is "thirty-one million, nine hundred seventy-one thousand, nine hundred forty".