31728019081639 has 4 divisors (see below), whose sum is σ = 31776164786520. Its totient is φ = 31679873376760.

The previous prime is 31728019081637. The next prime is 31728019081673. The reversal of 31728019081639 is 93618091082713.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 31728019081639 - 2¹ = 31728019081637 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31728019081637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24072851452 + ... + 24072852769.

It is an arithmetic number, because the mean of its divisors is an integer number (7944041196630).

Almost surely, 2^{31728019081639} is an apocalyptic number.

31728019081639 is a deficient number, since it is larger than the sum of its proper divisors (48145704881).

31728019081639 is an equidigital number, since it uses as much as digits as its factorization.

31728019081639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48145704880.

The product of its (nonzero) digits is 3919104, while the sum is 58.

The spelling of 31728019081639 in words is "thirty-one trillion, seven hundred twenty-eight billion, nineteen million, eighty-one thousand, six hundred thirty-nine".