21567221066 has 8 divisors (see below), whose sum is σ = 32360467044. Its totient is φ = 10780398720.

The previous prime is 21567221057. The next prime is 21567221069. The reversal of 21567221066 is 66012276512.

It can be written as a sum of positive squares in 2 ways, for example, as 19818726841 + 1748494225 = 140779^2 + 41815^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21567221069) 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, 1597505 + ... + 1610948.

Almost surely, 2^21567221066 is an apocalyptic number.

21567221066 is a deficient number, since it is larger than the sum of its proper divisors (10793245978).

21567221066 is a wasteful number, since it uses less digits than its factorization.

21567221066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3211816.

The product of its (nonzero) digits is 60480, while the sum is 38.

Adding to 21567221066 its reverse (66012276512), we get a palindrome (87579497578).

The spelling of 21567221066 in words is "twenty-one billion, five hundred sixty-seven million, two hundred twenty-one thousand, sixty-six".