21121210171 has 2 divisors, whose sum is σ = 21121210172. Its totient is φ = 21121210170.

The previous prime is 21121210153. The next prime is 21121210237. The reversal of 21121210171 is 17101212112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21121210171 - 2⁷ = 21121210043 is a prime.

It is a super-2 number, since 2×21121210171² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21121210151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560605085 + 10560605086.

It is an arithmetic number, because the mean of its divisors is an integer number (10560605086).

Almost surely, 2^21121210171 is an apocalyptic number.

21121210171 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121210171 is an equidigital number, since it uses as much as digits as its factorization.

21121210171 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 56, while the sum is 19.

Adding to 21121210171 its reverse (17101212112), we get a palindrome (38222422283).

The spelling of 21121210171 in words is "twenty-one billion, one hundred twenty-one million, two hundred ten thousand, one hundred seventy-one".