21681566226 has 12 divisors (see below), whose sum is σ = 46976726862. Its totient is φ = 7227188736.

The previous prime is 21681566219. The next prime is 21681566227. The reversal of 21681566226 is 62266518612.

21681566226 is a `hidden beast` number, since 2 + 1 + 6 + 8 + 15 + 6 + 622 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 21525291225 + 156275001 = 146715^2 + 12501^2 .

It is not an unprimeable number, because it can be changed into a prime (21681566227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 602265711 + ... + 602265746.

Almost surely, 2^21681566226 is an apocalyptic number.

21681566226 is an abundant number, since it is smaller than the sum of its proper divisors (25295160636).

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

21681566226 is a wasteful number, since it uses less digits than its factorization.

21681566226 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1204531465 (or 1204531462 counting only the distinct ones).

The product of its digits is 414720, while the sum is 45.

The spelling of 21681566226 in words is "twenty-one billion, six hundred eighty-one million, five hundred sixty-six thousand, two hundred twenty-six".