28155497617 has 4 divisors (see below), whose sum is σ = 30321305140. Its totient is φ = 25989690096.

The previous prime is 28155497609. The next prime is 28155497647. The reversal of 28155497617 is 71679455182.

It is a Cunningham number, because it is equal to 167796²+1.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4164895296 + 23990602321 = 64536^2 + 154889^2 .

It is a cyclic number.

It is not a de Polignac number, because 28155497617 - 2³ = 28155497609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28155497647) 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, 1082903742 + ... + 1082903767.

It is an arithmetic number, because the mean of its divisors is an integer number (7580326285).

Almost surely, 2^28155497617 is an apocalyptic number.

It is an amenable number.

28155497617 is a deficient number, since it is larger than the sum of its proper divisors (2165807523).

28155497617 is a wasteful number, since it uses less digits than its factorization.

28155497617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2165807522.

The product of its digits is 4233600, while the sum is 55.

The spelling of 28155497617 in words is "twenty-eight billion, one hundred fifty-five million, four hundred ninety-seven thousand, six hundred seventeen".