20685563 has 4 divisors (see below), whose sum is σ = 20834520. Its totient is φ = 20536608.

The previous prime is 20685559. The next prime is 20685569. The reversal of 20685563 is 36558602.

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 20685563 - 2² = 20685559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20685569) 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, 74270 + ... + 74547.

It is an arithmetic number, because the mean of its divisors is an integer number (5208630).

Almost surely, 2^20685563 is an apocalyptic number.

20685563 is a deficient number, since it is larger than the sum of its proper divisors (148957).

20685563 is a wasteful number, since it uses less digits than its factorization.

20685563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148956.

The product of its (nonzero) digits is 43200, while the sum is 35.

The square root of 20685563 is about 4548.1384103829. The cubic root of 20685563 is about 274.5084906404.

The spelling of 20685563 in words is "twenty million, six hundred eighty-five thousand, five hundred sixty-three".