213720217 has 2 divisors, whose sum is σ = 213720218. Its totient is φ = 213720216.

The previous prime is 213720187. The next prime is 213720263. The reversal of 213720217 is 712027312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 207475216 + 6245001 = 14404^2 + 2499^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-213720217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 213720191 and 213720200.

It is not a weakly prime, because it can be changed into another prime (213720817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106860108 + 106860109.

It is an arithmetic number, because the mean of its divisors is an integer number (106860109).

Almost surely, 2^213720217 is an apocalyptic number.

It is an amenable number.

213720217 is a deficient number, since it is larger than the sum of its proper divisors (1).

213720217 is an equidigital number, since it uses as much as digits as its factorization.

213720217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1176, while the sum is 25.

The square root of 213720217 is about 14619.1729246220. The cubic root of 213720217 is about 597.8816193896.

Adding to 213720217 its reverse (712027312), we get a palindrome (925747529).

The spelling of 213720217 in words is "two hundred thirteen million, seven hundred twenty thousand, two hundred seventeen".