217230529721 has 2 divisors, whose sum is σ = 217230529722. Its totient is φ = 217230529720.

The previous prime is 217230529693. The next prime is 217230529729. The reversal of 217230529721 is 127925032712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 191462254096 + 25768275625 = 437564^2 + 160525^2 .

It is a cyclic number.

It is not a de Polignac number, because 217230529721 - 2¹⁸ = 217230267577 is a prime.

It is not a weakly prime, because it can be changed into another prime (217230529729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108615264860 + 108615264861.

It is an arithmetic number, because the mean of its divisors is an integer number (108615264861).

Almost surely, 2^217230529721 is an apocalyptic number.

It is an amenable number.

217230529721 is a deficient number, since it is larger than the sum of its proper divisors (1).

217230529721 is an equidigital number, since it uses as much as digits as its factorization.

217230529721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 105840, while the sum is 41.

The spelling of 217230529721 in words is "two hundred seventeen billion, two hundred thirty million, five hundred twenty-nine thousand, seven hundred twenty-one".