28787877857 has 4 divisors (see below), whose sum is σ = 28803348756. Its totient is φ = 28772406960.

The previous prime is 28787877829. The next prime is 28787877893. The reversal of 28787877857 is 75877878782.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75877878782 = 2 ⋅37938939391.

It can be written as a sum of positive squares in 2 ways, for example, as 2670408976 + 26117468881 = 51676^2 + 161609^2 .

It is a cyclic number.

It is not a de Polignac number, because 28787877857 - 2³⁴ = 11608008673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28787877827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7732658 + ... + 7736379.

It is an arithmetic number, because the mean of its divisors is an integer number (7200837189).

Almost surely, 2^28787877857 is an apocalyptic number.

It is an amenable number.

28787877857 is a deficient number, since it is larger than the sum of its proper divisors (15470899).

28787877857 is a wasteful number, since it uses less digits than its factorization.

28787877857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15470898.

The product of its digits is 688414720, while the sum is 74.

The spelling of 28787877857 in words is "twenty-eight billion, seven hundred eighty-seven million, eight hundred seventy-seven thousand, eight hundred fifty-seven".