21221066705 has 16 divisors (see below), whose sum is σ = 25952100624. Its totient is φ = 16652463360.

The previous prime is 21221066701. The next prime is 21221066729. The reversal of 21221066705 is 50766012212.

It can be written as a sum of positive squares in 8 ways, for example, as 31315216 + 21189751489 = 5596^2 + 145567^2 .

It is not a de Polignac number, because 21221066705 - 2² = 21221066701 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221066701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1535687 + ... + 1549443.

It is an arithmetic number, because the mean of its divisors is an integer number (1622006289).

Almost surely, 2^21221066705 is an apocalyptic number.

It is an amenable number.

21221066705 is a deficient number, since it is larger than the sum of its proper divisors (4731033919).

21221066705 is a wasteful number, since it uses less digits than its factorization.

21221066705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19636.

The product of its (nonzero) digits is 10080, while the sum is 32.

Adding to 21221066705 its reverse (50766012212), we get a palindrome (71987078917).

The spelling of 21221066705 in words is "twenty-one billion, two hundred twenty-one million, sixty-six thousand, seven hundred five".