21320310217 has 2 divisors, whose sum is σ = 21320310218. Its totient is φ = 21320310216.

The previous prime is 21320310211. The next prime is 21320310227. The reversal of 21320310217 is 71201302312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13367059456 + 7953250761 = 115616^2 + 89181^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21320310217 is a prime.

It is a super-2 number, since 2×21320310217² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21320310211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660155108 + 10660155109.

It is an arithmetic number, because the mean of its divisors is an integer number (10660155109).

Almost surely, 2^21320310217 is an apocalyptic number.

It is an amenable number.

21320310217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21320310217 is an equidigital number, since it uses as much as digits as its factorization.

21320310217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 504, while the sum is 22.

Adding to 21320310217 its reverse (71201302312), we get a palindrome (92521612529).

The spelling of 21320310217 in words is "twenty-one billion, three hundred twenty million, three hundred ten thousand, two hundred seventeen".