20305613 has 4 divisors (see below), whose sum is σ = 20326560. Its totient is φ = 20284668.

The previous prime is 20305609. The next prime is 20305631. The reversal of 20305613 is 31650302.

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, and also an emirpimes, since its reverse is a distinct semiprime: 31650302 = 2 ⋅15825151.

It is a cyclic number.

It is not a de Polignac number, because 20305613 - 2² = 20305609 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 (20305603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8945 + ... + 10982.

It is an arithmetic number, because the mean of its divisors is an integer number (5081640).

Almost surely, 2^20305613 is an apocalyptic number.

It is an amenable number.

20305613 is a deficient number, since it is larger than the sum of its proper divisors (20947).

20305613 is a wasteful number, since it uses less digits than its factorization.

20305613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20946.

The product of its (nonzero) digits is 540, while the sum is 20.

The square root of 20305613 is about 4506.1749855060. The cubic root of 20305613 is about 272.8173806732.

Adding to 20305613 its reverse (31650302), we get a palindrome (51955915).

The spelling of 20305613 in words is "twenty million, three hundred five thousand, six hundred thirteen".