28639688781 has 8 divisors (see below), whose sum is σ = 41657729184. Its totient is φ = 17357387120.

The previous prime is 28639688767. The next prime is 28639688789. The reversal of 28639688781 is 18788693682.

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 28639688781 - 2²⁷ = 28505471053 is a prime.

It is a super-2 number, since 2×28639688781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28639688789) 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, 433934646 + ... + 433934711.

It is an arithmetic number, because the mean of its divisors is an integer number (5207216148).

Almost surely, 2^28639688781 is an apocalyptic number.

It is an amenable number.

28639688781 is a deficient number, since it is larger than the sum of its proper divisors (13018040403).

28639688781 is a wasteful number, since it uses less digits than its factorization.

28639688781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 867869371.

The product of its digits is 55738368, while the sum is 66.

The spelling of 28639688781 in words is "twenty-eight billion, six hundred thirty-nine million, six hundred eighty-eight thousand, seven hundred eighty-one".