21203213 has 2 divisors, whose sum is σ = 21203214. Its totient is φ = 21203212.

The previous prime is 21203197. The next prime is 21203219. The reversal of 21203213 is 31230212.

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., 19166884 + 2036329 = 4378^2 + 1427^2 .

It is a cyclic number.

It is not a de Polignac number, because 21203213 - 2⁴ = 21203197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21203219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601606 + 10601607.

It is an arithmetic number, because the mean of its divisors is an integer number (10601607).

Almost surely, 2^21203213 is an apocalyptic number.

It is an amenable number.

21203213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21203213 is an equidigital number, since it uses as much as digits as its factorization.

21203213 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21203213 is about 4604.6946695737. The cubic root of 21203213 is about 276.7794819024.

Adding to 21203213 its reverse (31230212), we get a palindrome (52433425).

The spelling of 21203213 in words is "twenty-one million, two hundred three thousand, two hundred thirteen".