21320213 has 2 divisors, whose sum is σ = 21320214. Its totient is φ = 21320212.

The previous prime is 21320209. The next prime is 21320239. The reversal of 21320213 is 31202312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20811844 + 508369 = 4562^2 + 713^2 .

It is a cyclic number.

It is not a de Polignac number, because 21320213 - 2² = 21320209 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21320203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660106 + 10660107.

It is an arithmetic number, because the mean of its divisors is an integer number (10660107).

Almost surely, 2^21320213 is an apocalyptic number.

It is an amenable number.

21320213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21320213 is an equidigital number, since it uses as much as digits as its factorization.

21320213 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 21320213 is about 4617.3816173238. The cubic root of 21320213 is about 277.2876410113.

Adding to 21320213 its reverse (31202312), we get a palindrome (52522525).

The spelling of 21320213 in words is "twenty-one million, three hundred twenty thousand, two hundred thirteen".