28131973985 has 8 divisors (see below), whose sum is σ = 33759390120. Its totient is φ = 22504898304.

The previous prime is 28131973981. The next prime is 28131973993. The reversal of 28131973985 is 58937913182.

It can be written as a sum of positive squares in 4 ways, for example, as 7573002529 + 20558971456 = 87023^2 + 143384^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28131973985 - 2² = 28131973981 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28131973985.

It is not an unprimeable number, because it can be changed into a prime (28131973981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161801 + ... + 287129.

It is an arithmetic number, because the mean of its divisors is an integer number (4219923765).

Almost surely, 2^28131973985 is an apocalyptic number.

It is an amenable number.

28131973985 is a deficient number, since it is larger than the sum of its proper divisors (5627416135).

28131973985 is a wasteful number, since it uses less digits than its factorization.

28131973985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170227.

The product of its digits is 3265920, while the sum is 56.

It can be divided in two parts, 2813197 and 3985, that added together give a palindrome (2817182).

The spelling of 28131973985 in words is "twenty-eight billion, one hundred thirty-one million, nine hundred seventy-three thousand, nine hundred eighty-five".