28691981177 has 2 divisors, whose sum is σ = 28691981178. Its totient is φ = 28691981176.

The previous prime is 28691981161. The next prime is 28691981233. The reversal of 28691981177 is 77118919682.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24639894841 + 4052086336 = 156971^2 + 63656^2 .

It is a cyclic number.

It is not a de Polignac number, because 28691981177 - 2⁴ = 28691981161 is a prime.

It is a super-2 number, since 2×28691981177² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (28691381177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14345990588 + 14345990589.

It is an arithmetic number, because the mean of its divisors is an integer number (14345990589).

Almost surely, 2^28691981177 is an apocalyptic number.

It is an amenable number.

28691981177 is a deficient number, since it is larger than the sum of its proper divisors (1).

28691981177 is an equidigital number, since it uses as much as digits as its factorization.

28691981177 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3048192, while the sum is 59.

The spelling of 28691981177 in words is "twenty-eight billion, six hundred ninety-one million, nine hundred eighty-one thousand, one hundred seventy-seven".