28178742637 has 4 divisors (see below), whose sum is σ = 28200604860. Its totient is φ = 28156880416.

The previous prime is 28178742589. The next prime is 28178742659. The reversal of 28178742637 is 73624787182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 73624787182 = 2 ⋅36812393591.

It can be written as a sum of positive squares in 2 ways, for example, as 18055565641 + 10123176996 = 134371^2 + 100614^2 .

It is a cyclic number.

It is not a de Polignac number, because 28178742637 - 2¹¹ = 28178740589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28178742937) 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, 10929178 + ... + 10931755.

It is an arithmetic number, because the mean of its divisors is an integer number (7050151215).

Almost surely, 2^28178742637 is an apocalyptic number.

It is an amenable number.

28178742637 is a deficient number, since it is larger than the sum of its proper divisors (21862223).

28178742637 is a wasteful number, since it uses less digits than its factorization.

28178742637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21862222.

The product of its digits is 6322176, while the sum is 55.

The spelling of 28178742637 in words is "twenty-eight billion, one hundred seventy-eight million, seven hundred forty-two thousand, six hundred thirty-seven".