21786278656 has 18 divisors (see below), whose sum is σ = 43487455172. Its totient is φ = 10893139200.

The previous prime is 21786278593. The next prime is 21786278669. The reversal of 21786278656 is 65687268712.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21786278656.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42551070 + ... + 42551581.

Almost surely, 2^21786278656 is an apocalyptic number.

It is an amenable number.

21786278656 is a deficient number, since it is larger than the sum of its proper divisors (21701176516).

21786278656 is an frugal number, since it uses more digits than its factorization.

21786278656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85102667 (or 85102653 counting only the distinct ones).

The product of its digits is 13547520, while the sum is 58.

The spelling of 21786278656 in words is "twenty-one billion, seven hundred eighty-six million, two hundred seventy-eight thousand, six hundred fifty-six".