31686340 has 96 divisors (see below), whose sum is σ = 80640000. Its totient is φ = 10442880.

The previous prime is 31686289. The next prime is 31686349. The reversal of 31686340 is 4368613.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a nialpdrome in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31686349) 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, 212586 + ... + 212734.

It is an arithmetic number, because the mean of its divisors is an integer number (840000).

Almost surely, 2^31686340 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 31686340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40320000).

31686340 is an abundant number, since it is smaller than the sum of its proper divisors (48953660).

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

31686340 is a wasteful number, since it uses less digits than its factorization.

31686340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210 (or 194 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 31686340 is about 5629.0620888386. The cubic root of 31686340 is about 316.4395022077.

The spelling of 31686340 in words is "thirty-one million, six hundred eighty-six thousand, three hundred forty".