21135613 has 2 divisors, whose sum is σ = 21135614. Its totient is φ = 21135612.

The previous prime is 21135593. The next prime is 21135637. The reversal of 21135613 is 31653112.

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., 11168964 + 9966649 = 3342^2 + 3157^2 .

It is a cyclic number.

It is not a de Polignac number, because 21135613 - 2¹⁷ = 21004541 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21135683) 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, 10567806 + 10567807.

It is an arithmetic number, because the mean of its divisors is an integer number (10567807).

Almost surely, 2^21135613 is an apocalyptic number.

It is an amenable number.

21135613 is a deficient number, since it is larger than the sum of its proper divisors (1).

21135613 is an equidigital number, since it uses as much as digits as its factorization.

21135613 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 540, while the sum is 22.

The square root of 21135613 is about 4597.3484749364. The cubic root of 21135613 is about 276.4850263357.

Adding to 21135613 its reverse (31653112), we get a palindrome (52788725).

The spelling of 21135613 in words is "twenty-one million, one hundred thirty-five thousand, six hundred thirteen".