20717563 has 4 divisors (see below), whose sum is σ = 20849680. Its totient is φ = 20585448.

The previous prime is 20717537. The next prime is 20717569. The reversal of 20717563 is 36571702.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20717563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20717569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65823 + ... + 66136.

It is an arithmetic number, because the mean of its divisors is an integer number (5212420).

Almost surely, 2^20717563 is an apocalyptic number.

20717563 is a deficient number, since it is larger than the sum of its proper divisors (132117).

20717563 is a wasteful number, since it uses less digits than its factorization.

20717563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132116.

The product of its (nonzero) digits is 8820, while the sum is 31.

The square root of 20717563 is about 4551.6549737431. The cubic root of 20717563 is about 274.6499700853.

The spelling of 20717563 in words is "twenty million, seven hundred seventeen thousand, five hundred sixty-three".