21184217 has 2 divisors, whose sum is σ = 21184218. Its totient is φ = 21184216.

The previous prime is 21184213. The next prime is 21184277. The reversal of 21184217 is 71248112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15713296 + 5470921 = 3964^2 + 2339^2 .

It is a cyclic number.

It is not a de Polignac number, because 21184217 - 2² = 21184213 is a prime.

It is not a weakly prime, because it can be changed into another prime (21184213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10592108 + 10592109.

It is an arithmetic number, because the mean of its divisors is an integer number (10592109).

Almost surely, 2^21184217 is an apocalyptic number.

It is an amenable number.

21184217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21184217 is an equidigital number, since it uses as much as digits as its factorization.

21184217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 896, while the sum is 26.

The square root of 21184217 is about 4602.6315298968. The cubic root of 21184217 is about 276.6968014465.

The spelling of 21184217 in words is "twenty-one million, one hundred eighty-four thousand, two hundred seventeen".