20561603473 has 4 divisors (see below), whose sum is σ = 20843269348. Its totient is φ = 20279937600.

The previous prime is 20561603459. The next prime is 20561603527. The reversal of 20561603473 is 37430616502.

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

It can be written as a sum of positive squares in 2 ways, for example, as 16105640464 + 4455963009 = 126908^2 + 66753^2 .

It is a cyclic number.

It is not a de Polignac number, because 20561603473 - 2⁵ = 20561603441 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20561600473) 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, 140832828 + ... + 140832973.

It is an arithmetic number, because the mean of its divisors is an integer number (5210817337).

Almost surely, 2^20561603473 is an apocalyptic number.

It is an amenable number.

20561603473 is a deficient number, since it is larger than the sum of its proper divisors (281665875).

20561603473 is an equidigital number, since it uses as much as digits as its factorization.

20561603473 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 281665874.

The product of its (nonzero) digits is 90720, while the sum is 37.

The spelling of 20561603473 in words is "twenty billion, five hundred sixty-one million, six hundred three thousand, four hundred seventy-three".