21100217 has 2 divisors, whose sum is σ = 21100218. Its totient is φ = 21100216.

The previous prime is 21100207. The next prime is 21100231. The reversal of 21100217 is 71200112.

It is an a-pointer prime, because the next prime (21100231) can be obtained adding 21100217 to its sum of digits (14).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14830201 + 6270016 = 3851^2 + 2504^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100217 - 2¹² = 21096121 is a prime.

It is not a weakly prime, because it can be changed into another prime (21100207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550108 + 10550109.

It is an arithmetic number, because the mean of its divisors is an integer number (10550109).

Almost surely, 2^21100217 is an apocalyptic number.

It is an amenable number.

21100217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100217 is an equidigital number, since it uses as much as digits as its factorization.

21100217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28, while the sum is 14.

The square root of 21100217 is about 4593.4972515503. The cubic root of 21100217 is about 276.3305961134.

Adding to 21100217 its reverse (71200112), we get a palindrome (92300329).

The spelling of 21100217 in words is "twenty-one million, one hundred thousand, two hundred seventeen".