21184213 has 2 divisors, whose sum is σ = 21184214. Its totient is φ = 21184212.

The previous prime is 21184187. The next prime is 21184217. The reversal of 21184213 is 31248112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17156164 + 4028049 = 4142^2 + 2007^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21184213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21184217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10592106 + 10592107.

It is an arithmetic number, because the mean of its divisors is an integer number (10592107).

Almost surely, 2^21184213 is an apocalyptic number.

It is an amenable number.

21184213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21184213 is an equidigital number, since it uses as much as digits as its factorization.

21184213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 384, while the sum is 22.

The square root of 21184213 is about 4602.6310953627. The cubic root of 21184213 is about 276.6967840312.

The spelling of 21184213 in words is "twenty-one million, one hundred eighty-four thousand, two hundred thirteen".