21221716202647 has 2 divisors, whose sum is σ = 21221716202648. Its totient is φ = 21221716202646.

The previous prime is 21221716202641. The next prime is 21221716202663. The reversal of 21221716202647 is 74620261712212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21221716202647 - 2³ = 21221716202639 is a prime.

It is a super-2 number, since 2×21221716202647² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221716202641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610858101323 + 10610858101324.

It is an arithmetic number, because the mean of its divisors is an integer number (10610858101324).

Almost surely, 2^{21221716202647} is an apocalyptic number.

21221716202647 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221716202647 is an equidigital number, since it uses as much as digits as its factorization.

21221716202647 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 225792, while the sum is 43.

Adding to 21221716202647 its reverse (74620261712212), we get a palindrome (95841977914859).

The spelling of 21221716202647 in words is "twenty-one trillion, two hundred twenty-one billion, seven hundred sixteen million, two hundred two thousand, six hundred forty-seven".