21335613 has 16 divisors (see below), whose sum is σ = 32249280. Its totient is φ = 12438144.

The previous prime is 21335597. The next prime is 21335617. The reversal of 21335613 is 31653312.

It is a happy number.

It is not a de Polignac number, because 21335613 - 2⁴ = 21335597 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21335617) 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 in 15 ways as a sum of consecutive naturals, for example, 13656 + ... + 15137.

It is an arithmetic number, because the mean of its divisors is an integer number (2015580).

Almost surely, 2^21335613 is an apocalyptic number.

It is an amenable number.

21335613 is a deficient number, since it is larger than the sum of its proper divisors (10913667).

21335613 is a wasteful number, since it uses less digits than its factorization.

21335613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28828.

The product of its digits is 1620, while the sum is 24.

The square root of 21335613 is about 4619.0489280803. The cubic root of 21335613 is about 277.3543883420.

Adding to 21335613 its reverse (31653312), we get a palindrome (52988925).

The spelling of 21335613 in words is "twenty-one million, three hundred thirty-five thousand, six hundred thirteen".