31308728 has 32 divisors (see below), whose sum is σ = 64955520. Its totient is φ = 14028000.

The previous prime is 31308709. The next prime is 31308779. The reversal of 31308728 is 82780313.

It is a junction number, because it is equal to n+sod(n) for n = 31308694 and 31308703.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3743 + ... + 8753.

It is an arithmetic number, because the mean of its divisors is an integer number (2029860).

Almost surely, 2^31308728 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 31308728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32477760).

31308728 is an abundant number, since it is smaller than the sum of its proper divisors (33646792).

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

31308728 is a wasteful number, since it uses less digits than its factorization.

31308728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5099 (or 5095 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 31308728 is about 5595.4202701853. The cubic root of 31308728 is about 315.1774527148.

The spelling of 31308728 in words is "thirty-one million, three hundred eight thousand, seven hundred twenty-eight".