31985840 has 80 divisors (see below), whose sum is σ = 81557280. Its totient is φ = 11612160.

The previous prime is 31985813. The next prime is 31985843. The reversal of 31985840 is 4858913.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 31985794 and 31985803.

It is not an unprimeable number, because it can be changed into a prime (31985843) 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, 39035 + ... + 39845.

It is an arithmetic number, because the mean of its divisors is an integer number (1019466).

Almost surely, 2^31985840 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 31985840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40778640).

31985840 is an abundant number, since it is smaller than the sum of its proper divisors (49571440).

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

31985840 is a wasteful number, since it uses less digits than its factorization.

31985840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 870 (or 864 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 31985840 is about 5655.6025320031. The cubic root of 31985840 is about 317.4333751537.

The spelling of 31985840 in words is "thirty-one million, nine hundred eighty-five thousand, eight hundred forty".