21174217 has 2 divisors, whose sum is σ = 21174218. Its totient is φ = 21174216.

The previous prime is 21174187. The next prime is 21174221. The reversal of 21174217 is 71247112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20620681 + 553536 = 4541^2 + 744^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21174217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21174191 and 21174200.

It is not a weakly prime, because it can be changed into another prime (21174617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10587108 + 10587109.

It is an arithmetic number, because the mean of its divisors is an integer number (10587109).

Almost surely, 2^21174217 is an apocalyptic number.

It is an amenable number.

21174217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21174217 is an equidigital number, since it uses as much as digits as its factorization.

21174217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 784, while the sum is 25.

The square root of 21174217 is about 4601.5450666053. The cubic root of 21174217 is about 276.6532563942.

The spelling of 21174217 in words is "twenty-one million, one hundred seventy-four thousand, two hundred seventeen".