31728755520 has 504 divisors, whose sum is σ = 137104111872. Its totient is φ = 6592481280.

The previous prime is 31728755501. The next prime is 31728755563. The reversal of 31728755520 is 2555782713.

31728755520 is a `hidden beast` number, since 3 + 1 + 7 + 28 + 75 + 552 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (504).

It is a Smith number, since the sum of its digits (45) 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 (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2432857 + ... + 2445863.

It is an arithmetic number, because the mean of its divisors is an integer number (272031968).

Almost surely, 2^31728755520 is an apocalyptic number.

31728755520 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31728755520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (68552055936).

31728755520 is an abundant number, since it is smaller than the sum of its proper divisors (105375356352).

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

31728755520 is a wasteful number, since it uses less digits than its factorization.

31728755520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13059 (or 13035 counting only the distinct ones).

The product of its (nonzero) digits is 588000, while the sum is 45.

The spelling of 31728755520 in words is "thirty-one billion, seven hundred twenty-eight million, seven hundred fifty-five thousand, five hundred twenty".