20305289 has 4 divisors (see below), whose sum is σ = 20348160. Its totient is φ = 20262420.

The previous prime is 20305277. The next prime is 20305321. The reversal of 20305289 is 98250302.

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 a de Polignac number, because none of the positive numbers 2^k-20305289 is a prime.

It is a super-2 number, since 2×20305289² = 824609522747042, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20305189) 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, 20717 + ... + 21674.

It is an arithmetic number, because the mean of its divisors is an integer number (5087040).

Almost surely, 2^20305289 is an apocalyptic number.

It is an amenable number.

20305289 is a deficient number, since it is larger than the sum of its proper divisors (42871).

20305289 is an equidigital number, since it uses as much as digits as its factorization.

20305289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42870.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 20305289 is about 4506.1390346948. The cubic root of 20305289 is about 272.8159296245.

The spelling of 20305289 in words is "twenty million, three hundred five thousand, two hundred eighty-nine".