21133213 has 2 divisors, whose sum is σ = 21133214. Its totient is φ = 21133212.

The previous prime is 21133153. The next prime is 21133219. The reversal of 21133213 is 31233112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20457529 + 675684 = 4523^2 + 822^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21133213 is a prime.

It is a super-2 number, since 2×21133213² = 893225383406738, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21133219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10566606 + 10566607.

It is an arithmetic number, because the mean of its divisors is an integer number (10566607).

Almost surely, 2^21133213 is an apocalyptic number.

It is an amenable number.

21133213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21133213 is an equidigital number, since it uses as much as digits as its factorization.

21133213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108, while the sum is 16.

The square root of 21133213 is about 4597.0874475041. The cubic root of 21133213 is about 276.4745607583.

Adding to 21133213 its reverse (31233112), we get a palindrome (52366325).

The spelling of 21133213 in words is "twenty-one million, one hundred thirty-three thousand, two hundred thirteen".