28729892781 has 16 divisors (see below), whose sum is σ = 45066499200. Its totient is φ = 18026599104.

The previous prime is 28729892701. The next prime is 28729892801. The reversal of 28729892781 is 18729892782.

28729892781 is a `hidden beast` number, since 287 + 2 + 9 + 89 + 278 + 1 = 666.

It is not a de Polignac number, because 28729892781 - 2²⁶ = 28662783917 is a prime.

It is a super-2 number, since 2×28729892781² (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 (28729892701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31295721 + ... + 31296638.

It is an arithmetic number, because the mean of its divisors is an integer number (2816656200).

Almost surely, 2^28729892781 is an apocalyptic number.

It is an amenable number.

28729892781 is a deficient number, since it is larger than the sum of its proper divisors (16336606419).

28729892781 is a wasteful number, since it uses less digits than its factorization.

28729892781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62592385 (or 62592379 counting only the distinct ones).

The product of its digits is 16257024, while the sum is 63.

Subtracting from 28729892781 its reverse (18729892782), we obtain a palindrome (9999999999).

The spelling of 28729892781 in words is "twenty-eight billion, seven hundred twenty-nine million, eight hundred ninety-two thousand, seven hundred eighty-one".