28555778661 has 8 divisors (see below), whose sum is σ = 40078285920. Its totient is φ = 18035228592.

The previous prime is 28555778653. The next prime is 28555778707. The reversal of 28555778661 is 16687755582.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28555778661 - 2³ = 28555778653 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 28555778595 and 28555778604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28555778561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 250489230 + ... + 250489343.

It is an arithmetic number, because the mean of its divisors is an integer number (5009785740).

Almost surely, 2^28555778661 is an apocalyptic number.

It is an amenable number.

28555778661 is a deficient number, since it is larger than the sum of its proper divisors (11522507259).

28555778661 is a wasteful number, since it uses less digits than its factorization.

28555778661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500978595.

The product of its digits is 28224000, while the sum is 60.

The spelling of 28555778661 in words is "twenty-eight billion, five hundred fifty-five million, seven hundred seventy-eight thousand, six hundred sixty-one".