28781566639 has 8 divisors (see below), whose sum is σ = 33564509600. Its totient is φ = 24669913968.

The previous prime is 28781566633. The next prime is 28781566651. The reversal of 28781566639 is 93666518782.

It is not a de Polignac number, because 28781566639 - 2¹⁷ = 28781435567 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28781566633) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41955294 + ... + 41955979.

It is an arithmetic number, because the mean of its divisors is an integer number (4195563700).

Almost surely, 2^28781566639 is an apocalyptic number.

28781566639 is a deficient number, since it is larger than the sum of its proper divisors (4782942961).

28781566639 is an frugal number, since it uses more digits than its factorization.

28781566639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83911294 (or 83911280 counting only the distinct ones).

The product of its digits is 26127360, while the sum is 61.

The spelling of 28781566639 in words is "twenty-eight billion, seven hundred eighty-one million, five hundred sixty-six thousand, six hundred thirty-nine".