21267716656 has 20 divisors (see below), whose sum is σ = 42535434304. Its totient is φ = 10290830400.

The previous prime is 21267716653. The next prime is 21267716681. The reversal of 21267716656 is 65661776212.

21267716656 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21267716653) 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, 21438735 + ... + 21439726.

Almost surely, 2^21267716656 is an apocalyptic number.

It is an amenable number.

21267716656 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.

21267716656 is a wasteful number, since it uses less digits than its factorization.

21267716656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42878500 (or 42878494 counting only the distinct ones).

The product of its digits is 1270080, while the sum is 49.

The spelling of 21267716656 in words is "twenty-one billion, two hundred sixty-seven million, seven hundred sixteen thousand, six hundred fifty-six".