20563645 has 8 divisors (see below), whose sum is σ = 24820056. Its totient is φ = 16355136.

The previous prime is 20563637. The next prime is 20563651. The reversal of 20563645 is 54636502.

It can be written as a sum of positive squares in 4 ways, for example, as 3481956 + 17081689 = 1866^2 + 4133^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20563645 - 2³ = 20563637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11022 + ... + 12751.

It is an arithmetic number, because the mean of its divisors is an integer number (3102507).

Almost surely, 2^20563645 is an apocalyptic number.

It is an amenable number.

20563645 is a deficient number, since it is larger than the sum of its proper divisors (4256411).

20563645 is a wasteful number, since it uses less digits than its factorization.

20563645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23951.

The product of its (nonzero) digits is 21600, while the sum is 31.

The square root of 20563645 is about 4534.7155368336. The cubic root of 20563645 is about 273.9681219240.

The spelling of 20563645 in words is "twenty million, five hundred sixty-three thousand, six hundred forty-five".