28317778217 has 2 divisors, whose sum is σ = 28317778218. Its totient is φ = 28317778216.

The previous prime is 28317778189. The next prime is 28317778243. The reversal of 28317778217 is 71287771382.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26106803776 + 2210974441 = 161576^2 + 47021^2 .

It is a cyclic number.

It is not a de Polignac number, because 28317778217 - 2¹⁰ = 28317777193 is a prime.

It is not a weakly prime, because it can be changed into another prime (28317778817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14158889108 + 14158889109.

It is an arithmetic number, because the mean of its divisors is an integer number (14158889109).

Almost surely, 2^28317778217 is an apocalyptic number.

It is an amenable number.

28317778217 is a deficient number, since it is larger than the sum of its proper divisors (1).

28317778217 is an equidigital number, since it uses as much as digits as its factorization.

28317778217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1843968, while the sum is 53.

The spelling of 28317778217 in words is "twenty-eight billion, three hundred seventeen million, seven hundred seventy-eight thousand, two hundred seventeen".