21042013 has 2 divisors, whose sum is σ = 21042014. Its totient is φ = 21042012.

The previous prime is 21041989. The next prime is 21042017. The reversal of 21042013 is 31024012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21040569 + 1444 = 4587^2 + 38^2 .

It is a cyclic number.

It is not a de Polignac number, because 21042013 - 2⁵ = 21041981 is a prime.

It is a super-2 number, since 2×21042013² = 885532622184338, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21041984 and 21042002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21042017) 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, 10521006 + 10521007.

It is an arithmetic number, because the mean of its divisors is an integer number (10521007).

Almost surely, 2^21042013 is an apocalyptic number.

It is an amenable number.

21042013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21042013 is an equidigital number, since it uses as much as digits as its factorization.

21042013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21042013 is about 4587.1573986512. The cubic root of 21042013 is about 276.0762802881.

Adding to 21042013 its reverse (31024012), we get a palindrome (52066025).

The spelling of 21042013 in words is "twenty-one million, forty-two thousand, thirteen".