21043313 has 2 divisors, whose sum is σ = 21043314. Its totient is φ = 21043312.

The previous prime is 21043301. The next prime is 21043339. The reversal of 21043313 is 31334012.

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., 12794929 + 8248384 = 3577^2 + 2872^2 .

It is a cyclic number.

It is not a de Polignac number, because 21043313 - 2¹⁰ = 21042289 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21043291 and 21043300.

It is not a weakly prime, because it can be changed into another prime (21043613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521656 + 10521657.

It is an arithmetic number, because the mean of its divisors is an integer number (10521657).

Almost surely, 2^21043313 is an apocalyptic number.

It is an amenable number.

21043313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21043313 is an equidigital number, since it uses as much as digits as its factorization.

21043313 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 17.

The square root of 21043313 is about 4587.2990964183. The cubic root of 21043313 is about 276.0819656088.

Adding to 21043313 its reverse (31334012), we get a palindrome (52377325).

The spelling of 21043313 in words is "twenty-one million, forty-three thousand, three hundred thirteen".