21221201222171 has 2 divisors, whose sum is σ = 21221201222172. Its totient is φ = 21221201222170.

The previous prime is 21221201222161. The next prime is 21221201222201. The reversal of 21221201222171 is 17122210212212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221201222171 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21221201222171.

It is not a weakly prime, because it can be changed into another prime (21221201222161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610600611085 + 10610600611086.

It is an arithmetic number, because the mean of its divisors is an integer number (10610600611086).

Almost surely, 2^{21221201222171} is an apocalyptic number.

21221201222171 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221201222171 is an equidigital number, since it uses as much as digits as its factorization.

21221201222171 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 896, while the sum is 26.

Adding to 21221201222171 its reverse (17122210212212), we get a palindrome (38343411434383).

The spelling of 21221201222171 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred one million, two hundred twenty-two thousand, one hundred seventy-one".