31680720 has 100 divisors (see below), whose sum is σ = 110054340. Its totient is φ = 8446464.

The previous prime is 31680709. The next prime is 31680721. The reversal of 31680720 is 2708613.

It can be written as a sum of positive squares in 2 ways, for example, as 16842816 + 14837904 = 4104^2 + 3852^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31680721) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4036 + ... + 8924.

Almost surely, 2^31680720 is an apocalyptic number.

31680720 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31680720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (55027170).

31680720 is an abundant number, since it is smaller than the sum of its proper divisors (78373620).

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

31680720 is a wasteful number, since it uses less digits than its factorization.

31680720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4914 (or 4899 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 31680720 is about 5628.5628716396. The cubic root of 31680720 is about 316.4207928295.

It can be divided in two parts, 31680 and 720, that added together give a square (32400 = 180²).

The spelling of 31680720 in words is "thirty-one million, six hundred eighty thousand, seven hundred twenty".