20718563 has 4 divisors (see below), whose sum is σ = 21937320. Its totient is φ = 19499808.

The previous prime is 20718547. The next prime is 20718583. The reversal of 20718563 is 36581702.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20718563 - 2⁴ = 20718547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20718583) 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, 609353 + ... + 609386.

It is an arithmetic number, because the mean of its divisors is an integer number (5484330).

Almost surely, 2^20718563 is an apocalyptic number.

20718563 is a deficient number, since it is larger than the sum of its proper divisors (1218757).

20718563 is a wasteful number, since it uses less digits than its factorization.

20718563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1218756.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 20718563 is about 4551.7648225716. The cubic root of 20718563 is about 274.6543889698.

The spelling of 20718563 in words is "twenty million, seven hundred eighteen thousand, five hundred sixty-three".