28281516257 has 4 divisors (see below), whose sum is σ = 28355358720. Its totient is φ = 28207673796.

The previous prime is 28281516253. The next prime is 28281516293. The reversal of 28281516257 is 75261518282.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75261518282 = 2 ⋅37630759141.

It is a cyclic number.

It is not a de Polignac number, because 28281516257 - 2² = 28281516253 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28281516253) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36920657 + ... + 36921422.

It is an arithmetic number, because the mean of its divisors is an integer number (7088839680).

Almost surely, 2^28281516257 is an apocalyptic number.

It is an amenable number.

28281516257 is a deficient number, since it is larger than the sum of its proper divisors (73842463).

28281516257 is an equidigital number, since it uses as much as digits as its factorization.

28281516257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73842462.

The product of its digits is 537600, while the sum is 47.

The spelling of 28281516257 in words is "twenty-eight billion, two hundred eighty-one million, five hundred sixteen thousand, two hundred fifty-seven".