21338813 has 2 divisors, whose sum is σ = 21338814. Its totient is φ = 21338812.

The previous prime is 21338797. The next prime is 21338831. The reversal of 21338813 is 31883312.

Together with next prime (21338831) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18335524 + 3003289 = 4282^2 + 1733^2 .

It is a cyclic number.

It is not a de Polignac number, because 21338813 - 2⁴ = 21338797 is a prime.

It is a Chen prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21338833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10669406 + 10669407.

It is an arithmetic number, because the mean of its divisors is an integer number (10669407).

Almost surely, 2^21338813 is an apocalyptic number.

It is an amenable number.

21338813 is a deficient number, since it is larger than the sum of its proper divisors (1).

21338813 is an equidigital number, since it uses as much as digits as its factorization.

21338813 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 29.

The square root of 21338813 is about 4619.3953067474. The cubic root of 21338813 is about 277.3682538865.

The spelling of 21338813 in words is "twenty-one million, three hundred thirty-eight thousand, eight hundred thirteen".