21212017 has 2 divisors, whose sum is σ = 21212018. Its totient is φ = 21212016.

The previous prime is 21211997. The next prime is 21212033. The reversal of 21212017 is 71021212.

It is an a-pointer prime, because the next prime (21212033) can be obtained adding 21212017 to its sum of digits (16).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20214016 + 998001 = 4496^2 + 999^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212017 - 2²³ = 12823409 is a prime.

It is not a weakly prime, because it can be changed into another prime (21212077) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606008 + 10606009.

It is an arithmetic number, because the mean of its divisors is an integer number (10606009).

Almost surely, 2^21212017 is an apocalyptic number.

It is an amenable number.

21212017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212017 is an equidigital number, since it uses as much as digits as its factorization.

21212017 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56, while the sum is 16.

The square root of 21212017 is about 4605.6505512251. The cubic root of 21212017 is about 276.8177847353.

Adding to 21212017 its reverse (71021212), we get a palindrome (92233229).

The spelling of 21212017 in words is "twenty-one million, two hundred twelve thousand, seventeen".