20305643 has 2 divisors, whose sum is σ = 20305644. Its totient is φ = 20305642.

The previous prime is 20305631. The next prime is 20305657. The reversal of 20305643 is 34650302.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20305643 - 2¹⁰ = 20304619 is a prime.

It is not a weakly prime, because it can be changed into another prime (20305603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10152821 + 10152822.

It is an arithmetic number, because the mean of its divisors is an integer number (10152822).

Almost surely, 2^20305643 is an apocalyptic number.

20305643 is a deficient number, since it is larger than the sum of its proper divisors (1).

20305643 is an equidigital number, since it uses as much as digits as its factorization.

20305643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 23.

The square root of 20305643 is about 4506.1783142703. The cubic root of 20305643 is about 272.8175150288.

Adding to 20305643 its reverse (34650302), we get a palindrome (54955945).

The spelling of 20305643 in words is "twenty million, three hundred five thousand, six hundred forty-three".