21002122171 has 2 divisors, whose sum is σ = 21002122172. Its totient is φ = 21002122170.

The previous prime is 21002122159. The next prime is 21002122213. The reversal of 21002122171 is 17122120012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21002122171 - 2⁹ = 21002121659 is a prime.

It is not a weakly prime, because it can be changed into another prime (21002120171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501061085 + 10501061086.

It is an arithmetic number, because the mean of its divisors is an integer number (10501061086).

Almost surely, 2^21002122171 is an apocalyptic number.

21002122171 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002122171 is an equidigital number, since it uses as much as digits as its factorization.

21002122171 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 112, while the sum is 19.

Adding to 21002122171 its reverse (17122120012), we get a palindrome (38124242183).

The spelling of 21002122171 in words is "twenty-one billion, two million, one hundred twenty-two thousand, one hundred seventy-one".