28128747771 has 20 divisors (see below), whose sum is σ = 44231041800. Its totient is φ = 17765523936.

The previous prime is 28128747739. The next prime is 28128747797. The reversal of 28128747771 is 17774782182.

28128747771 is a `hidden beast` number, since 2 + 81 + 28 + 7 + 477 + 71 = 666.

It is not a de Polignac number, because 28128747771 - 2⁵ = 28128747739 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28128747701) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 9137106 + ... + 9140183.

It is an arithmetic number, because the mean of its divisors is an integer number (2211552090).

Almost surely, 2^28128747771 is an apocalyptic number.

28128747771 is a deficient number, since it is larger than the sum of its proper divisors (16102294029).

28128747771 is a wasteful number, since it uses less digits than its factorization.

28128747771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18277320 (or 18277311 counting only the distinct ones).

The product of its digits is 2458624, while the sum is 54.

The spelling of 28128747771 in words is "twenty-eight billion, one hundred twenty-eight million, seven hundred forty-seven thousand, seven hundred seventy-one".