171716212721 has 2 divisors, whose sum is σ = 171716212722. Its totient is φ = 171716212720.

The previous prime is 171716212699. The next prime is 171716212753. The reversal of 171716212721 is 127212617171.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 107167188496 + 64549024225 = 327364^2 + 254065^2 .

It is an emirp because it is prime and its reverse (127212617171) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 171716212721 - 2¹⁰ = 171716211697 is a prime.

It is a super-2 number, since 2×171716212721² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (171716262721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85858106360 + 85858106361.

It is an arithmetic number, because the mean of its divisors is an integer number (85858106361).

Almost surely, 2^171716212721 is an apocalyptic number.

It is an amenable number.

171716212721 is a deficient number, since it is larger than the sum of its proper divisors (1).

171716212721 is an equidigital number, since it uses as much as digits as its factorization.

171716212721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16464, while the sum is 38.

Adding to 171716212721 its reverse (127212617171), we get a palindrome (298928829892).

The spelling of 171716212721 in words is "one hundred seventy-one billion, seven hundred sixteen million, two hundred twelve thousand, seven hundred twenty-one".