21066013 has 2 divisors, whose sum is σ = 21066014. Its totient is φ = 21066012.

The previous prime is 21066007. The next prime is 21066049. The reversal of 21066013 is 31066012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20994724 + 71289 = 4582^2 + 267^2 .

It is a cyclic number.

It is not a de Polignac number, because 21066013 - 2⁹ = 21065501 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21066113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10533006 + 10533007.

It is an arithmetic number, because the mean of its divisors is an integer number (10533007).

Almost surely, 2^21066013 is an apocalyptic number.

It is an amenable number.

21066013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21066013 is an equidigital number, since it uses as much as digits as its factorization.

21066013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 21066013 is about 4589.7726523217. The cubic root of 21066013 is about 276.1812023352.

Subtracting 21066013 from its reverse (31066012), we obtain a palindrome (9999999).

The spelling of 21066013 in words is "twenty-one million, sixty-six thousand, thirteen".