31528728 has 192 divisors, whose sum is σ = 109624320. Its totient is φ = 8015040.

The previous prime is 31528723. The next prime is 31528729. The reversal of 31528728 is 82782513.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

Its product of digits (26880) is a multiple of the sum of its prime divisors (70).

It is a junction number, because it is equal to n+sod(n) for n = 31528692 and 31528701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31528723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 670801 + ... + 670847.

It is an arithmetic number, because the mean of its divisors is an integer number (570960).

Almost surely, 2^31528728 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 31528728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (54812160).

31528728 is an abundant number, since it is smaller than the sum of its proper divisors (78095592).

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

31528728 is a wasteful number, since it uses less digits than its factorization.

31528728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99 (or 70 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 31528728 is about 5615.0447905604. The cubic root of 31528728 is about 315.9139593768.

The spelling of 31528728 in words is "thirty-one million, five hundred twenty-eight thousand, seven hundred twenty-eight".