31330728 has 192 divisors, whose sum is σ = 106142400. Its totient is φ = 8202240.

The previous prime is 31330727. The next prime is 31330729. The reversal of 31330728 is 82703313.

It is an interprime number because it is at equal distance from previous prime (31330727) and next prime (31330729).

It is a super-2 number, since 2×31330728² = 1963229034019968, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (31330721) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 174943 + ... + 175121.

It is an arithmetic number, because the mean of its divisors is an integer number (552825).

Almost surely, 2^31330728 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 31330728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (53071200).

31330728 is an abundant number, since it is smaller than the sum of its proper divisors (74811672).

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

31330728 is a wasteful number, since it uses less digits than its factorization.

31330728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 232 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 27.

The square root of 31330728 is about 5597.3858183977. The cubic root of 31330728 is about 315.2512583374.

The spelling of 31330728 in words is "thirty-one million, three hundred thirty thousand, seven hundred twenty-eight".