217608221321 has 2 divisors, whose sum is σ = 217608221322. Its totient is φ = 217608221320.

The previous prime is 217608221309. The next prime is 217608221431. The reversal of 217608221321 is 123122806712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 157935502921 + 59672718400 = 397411^2 + 244280^2 .

It is a cyclic number.

It is not a de Polignac number, because 217608221321 - 2¹⁴ = 217608204937 is a prime.

It is not a weakly prime, because it can be changed into another prime (217608221921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108804110660 + 108804110661.

It is an arithmetic number, because the mean of its divisors is an integer number (108804110661).

Almost surely, 2^217608221321 is an apocalyptic number.

It is an amenable number.

217608221321 is a deficient number, since it is larger than the sum of its proper divisors (1).

217608221321 is an equidigital number, since it uses as much as digits as its factorization.

217608221321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 35.

The spelling of 217608221321 in words is "two hundred seventeen billion, six hundred eight million, two hundred twenty-one thousand, three hundred twenty-one".