28178887861 has 4 divisors (see below), whose sum is σ = 28205447724. Its totient is φ = 28152328000.

The previous prime is 28178887853. The next prime is 28178887883. The reversal of 28178887861 is 16878887182.

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 19535652900 + 8643234961 = 139770^2 + 92969^2 .

It is a cyclic number.

It is not a de Polignac number, because 28178887861 - 2³ = 28178887853 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28178887793 and 28178887802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28178827861) 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, 13278340 + ... + 13280461.

It is an arithmetic number, because the mean of its divisors is an integer number (7051361931).

Almost surely, 2^28178887861 is an apocalyptic number.

It is an amenable number.

28178887861 is a deficient number, since it is larger than the sum of its proper divisors (26559863).

28178887861 is a wasteful number, since it uses less digits than its factorization.

28178887861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26559862.

The product of its digits is 19267584, while the sum is 64.

The spelling of 28178887861 in words is "twenty-eight billion, one hundred seventy-eight million, eight hundred eighty-seven thousand, eight hundred sixty-one".