217221602621 has 2 divisors, whose sum is σ = 217221602622. Its totient is φ = 217221602620.

The previous prime is 217221602597. The next prime is 217221602623. The reversal of 217221602621 is 126206122712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 208588591225 + 8633011396 = 456715^2 + 92914^2 .

It is a cyclic number.

It is not a de Polignac number, because 217221602621 - 2¹⁴ = 217221586237 is a prime.

Together with 217221602623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217221602623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108610801310 + 108610801311.

It is an arithmetic number, because the mean of its divisors is an integer number (108610801311).

Almost surely, 2^217221602621 is an apocalyptic number.

It is an amenable number.

217221602621 is a deficient number, since it is larger than the sum of its proper divisors (1).

217221602621 is an equidigital number, since it uses as much as digits as its factorization.

217221602621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8064, while the sum is 32.

The spelling of 217221602621 in words is "two hundred seventeen billion, two hundred twenty-one million, six hundred two thousand, six hundred twenty-one".