21043270217 has 2 divisors, whose sum is σ = 21043270218. Its totient is φ = 21043270216.

The previous prime is 21043270201. The next prime is 21043270219. The reversal of 21043270217 is 71207234012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20233355536 + 809914681 = 142244^2 + 28459^2 .

It is a cyclic number.

It is not a de Polignac number, because 21043270217 - 2⁴ = 21043270201 is a prime.

Together with 21043270219, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21043270217.

It is not a weakly prime, because it can be changed into another prime (21043270219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521635108 + 10521635109.

It is an arithmetic number, because the mean of its divisors is an integer number (10521635109).

Almost surely, 2^21043270217 is an apocalyptic number.

It is an amenable number.

21043270217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21043270217 is an equidigital number, since it uses as much as digits as its factorization.

21043270217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4704, while the sum is 29.

The spelling of 21043270217 in words is "twenty-one billion, forty-three million, two hundred seventy thousand, two hundred seventeen".