21778816108 has 12 divisors (see below), whose sum is σ = 43557632272. Its totient is φ = 9333778320.

The previous prime is 21778816097. The next prime is 21778816133. The reversal of 21778816108 is 80161887712.

21778816108 is an admirable number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 388907403 + ... + 388907458.

Almost surely, 2^21778816108 is an apocalyptic number.

21778816108 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21778816108 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21778816108 is a wasteful number, since it uses less digits than its factorization.

21778816108 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 777814872 (or 777814870 counting only the distinct ones).

The product of its (nonzero) digits is 301056, while the sum is 49.

The spelling of 21778816108 in words is "twenty-one billion, seven hundred seventy-eight million, eight hundred sixteen thousand, one hundred eight".