21345613 has 4 divisors (see below), whose sum is σ = 21369760. Its totient is φ = 21321468.

The previous prime is 21345593. The next prime is 21345619. The reversal of 21345613 is 31654312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21345613 - 2⁹ = 21345101 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21345619) 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 3 ways as a sum of consecutive naturals, for example, 10695 + ... + 12532.

It is an arithmetic number, because the mean of its divisors is an integer number (5342440).

Almost surely, 2^21345613 is an apocalyptic number.

It is an amenable number.

21345613 is a deficient number, since it is larger than the sum of its proper divisors (24147).

21345613 is an equidigital number, since it uses as much as digits as its factorization.

21345613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24146.

The product of its digits is 2160, while the sum is 25.

The square root of 21345613 is about 4620.1312751912. The cubic root of 21345613 is about 277.3977135667.

Adding to 21345613 its reverse (31654312), we get a palindrome (52999925).

The spelling of 21345613 in words is "twenty-one million, three hundred forty-five thousand, six hundred thirteen".