28617779891 has 2 divisors, whose sum is σ = 28617779892. Its totient is φ = 28617779890.

The previous prime is 28617779863. The next prime is 28617779929. The reversal of 28617779891 is 19897771682.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28617779891 is a prime.

It is not a weakly prime, because it can be changed into another prime (28617779291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14308889945 + 14308889946.

It is an arithmetic number, because the mean of its divisors is an integer number (14308889946).

Almost surely, 2^28617779891 is an apocalyptic number.

28617779891 is a deficient number, since it is larger than the sum of its proper divisors (1).

28617779891 is an equidigital number, since it uses as much as digits as its factorization.

28617779891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21337344, while the sum is 65.

The spelling of 28617779891 in words is "twenty-eight billion, six hundred seventeen million, seven hundred seventy-nine thousand, eight hundred ninety-one".