21667221667 has 64 divisors (see below), whose sum is σ = 28601524224. Its totient is φ = 15927736320.

The previous prime is 21667221637. The next prime is 21667221677. The reversal of 21667221667 is 76612276612.

It is a cyclic number.

It is not a de Polignac number, because 21667221667 - 2¹⁵ = 21667188899 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21667221637) 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 63 ways as a sum of consecutive naturals, for example, 62441388 + ... + 62441734.

It is an arithmetic number, because the mean of its divisors is an integer number (446898816).

Almost surely, 2^21667221667 is an apocalyptic number.

21667221667 is a deficient number, since it is larger than the sum of its proper divisors (6934302557).

21667221667 is a wasteful number, since it uses less digits than its factorization.

21667221667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 788.

The product of its digits is 508032, while the sum is 46.

Subtracting 21667221667 from its reverse (76612276612), we obtain a palindrome (54945054945).

The spelling of 21667221667 in words is "twenty-one billion, six hundred sixty-seven million, two hundred twenty-one thousand, six hundred sixty-seven".