21211313171 has 2 divisors, whose sum is σ = 21211313172. Its totient is φ = 21211313170.

The previous prime is 21211313143. The next prime is 21211313173. The reversal of 21211313171 is 17131311212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211313171 is a prime.

Together with 21211313173, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21211313173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605656585 + 10605656586.

It is an arithmetic number, because the mean of its divisors is an integer number (10605656586).

Almost surely, 2^21211313171 is an apocalyptic number.

21211313171 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211313171 is an equidigital number, since it uses as much as digits as its factorization.

21211313171 is an evil number, because the sum of its binary digits is even.

The product of its digits is 252, while the sum is 23.

Adding to 21211313171 its reverse (17131311212), we get a palindrome (38342624383).

The spelling of 21211313171 in words is "twenty-one billion, two hundred eleven million, three hundred thirteen thousand, one hundred seventy-one".