21536213 has 2 divisors, whose sum is σ = 21536214. Its totient is φ = 21536212.

The previous prime is 21536191. The next prime is 21536261. The reversal of 21536213 is 31263512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20729809 + 806404 = 4553^2 + 898^2 .

It is a cyclic number.

It is not a de Polignac number, because 21536213 - 2⁶ = 21536149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21536113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10768106 + 10768107.

It is an arithmetic number, because the mean of its divisors is an integer number (10768107).

Almost surely, 2^21536213 is an apocalyptic number.

It is an amenable number.

21536213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21536213 is an equidigital number, since it uses as much as digits as its factorization.

21536213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1080, while the sum is 23.

The square root of 21536213 is about 4640.7125530461. The cubic root of 21536213 is about 278.2209180255.

Adding to 21536213 its reverse (31263512), we get a palindrome (52799725).

The spelling of 21536213 in words is "twenty-one million, five hundred thirty-six thousand, two hundred thirteen".