31140720 has 160 divisors (see below), whose sum is σ = 115617600. Its totient is φ = 7658496.

The previous prime is 31140679. The next prime is 31140727. The reversal of 31140720 is 2704113.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 31140693 and 31140702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31140727) 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, 27526 + ... + 28634.

It is an arithmetic number, because the mean of its divisors is an integer number (722610).

Almost surely, 2^31140720 is an apocalyptic number.

31140720 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 31140720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (57808800).

31140720 is an abundant number, since it is smaller than the sum of its proper divisors (84476880).

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

31140720 is a wasteful number, since it uses less digits than its factorization.

31140720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1144 (or 1132 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 31140720 is about 5580.3870833483. The cubic root of 31140720 is about 314.6126758687.

Adding to 31140720 its reverse (2704113), we get a palindrome (33844833).

The spelling of 31140720 in words is "thirty-one million, one hundred forty thousand, seven hundred twenty".