31728390 has 16 divisors (see below), whose sum is σ = 76148208. Its totient is φ = 8460896.

The previous prime is 31728353. The next prime is 31728421. The reversal of 31728390 is 9382713.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 528777 + ... + 528836.

It is an arithmetic number, because the mean of its divisors is an integer number (4759263).

Almost surely, 2^31728390 is an apocalyptic number.

31728390 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

31728390 is an abundant number, since it is smaller than the sum of its proper divisors (44419818).

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

31728390 is a wasteful number, since it uses less digits than its factorization.

31728390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1057623.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 31728390 is about 5632.7959309742. The cubic root of 31728390 is about 316.5794194852.

The spelling of 31728390 in words is "thirty-one million, seven hundred twenty-eight thousand, three hundred ninety".