31306728 has 32 divisors (see below), whose sum is σ = 78593760. Its totient is φ = 10392000.

The previous prime is 31306727. The next prime is 31306753. The reversal of 31306728 is 82760313.

It is a super-2 number, since 2×31306728² = 1960222436131968, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 31306695 and 31306704.

It is not an unprimeable number, because it can be changed into a prime (31306721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3426 + ... + 8622.

It is an arithmetic number, because the mean of its divisors is an integer number (2456055).

Almost surely, 2^31306728 is an apocalyptic number.

It is an amenable number.

31306728 is an abundant number, since it is smaller than the sum of its proper divisors (47287032).

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

31306728 is a wasteful number, since it uses less digits than its factorization.

31306728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5457 (or 5453 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 30.

The square root of 31306728 is about 5595.2415497456. The cubic root of 31306728 is about 315.1707413985.

The spelling of 31306728 in words is "thirty-one million, three hundred six thousand, seven hundred twenty-eight".