21666021105 has 8 divisors (see below), whose sum is σ = 34665633792. Its totient is φ = 11555211248.

The previous prime is 21666021077. The next prime is 21666021107. The reversal of 21666021105 is 50112066612.

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

It is a cyclic number.

It is not a de Polignac number, because 21666021105 - 2⁵ = 21666021073 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21666021107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 722200689 + ... + 722200718.

It is an arithmetic number, because the mean of its divisors is an integer number (4333204224).

Almost surely, 2^21666021105 is an apocalyptic number.

It is an amenable number.

21666021105 is a deficient number, since it is larger than the sum of its proper divisors (12999612687).

21666021105 is a wasteful number, since it uses less digits than its factorization.

21666021105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1444401415.

The product of its (nonzero) digits is 4320, while the sum is 30.

Adding to 21666021105 its reverse (50112066612), we get a palindrome (71778087717).

The spelling of 21666021105 in words is "twenty-one billion, six hundred sixty-six million, twenty-one thousand, one hundred five".