28081646557 has 2 divisors, whose sum is σ = 28081646558. Its totient is φ = 28081646556.

The previous prime is 28081646533. The next prime is 28081646627. The reversal of 28081646557 is 75564618082.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28039837401 + 41809156 = 167451^2 + 6466^2 .

It is a cyclic number.

It is not a de Polignac number, because 28081646557 - 2¹⁵ = 28081613789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28081646507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14040823278 + 14040823279.

It is an arithmetic number, because the mean of its divisors is an integer number (14040823279).

Almost surely, 2^28081646557 is an apocalyptic number.

It is an amenable number.

28081646557 is a deficient number, since it is larger than the sum of its proper divisors (1).

28081646557 is an equidigital number, since it uses as much as digits as its factorization.

28081646557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3225600, while the sum is 52.

The spelling of 28081646557 in words is "twenty-eight billion, eighty-one million, six hundred forty-six thousand, five hundred fifty-seven".