20561603447 has 32 divisors (see below), whose sum is σ = 25993612800. Its totient is φ = 15931227840.

The previous prime is 20561603441. The next prime is 20561603459. The reversal of 20561603447 is 74430616502.

It is a happy number.

It is not a de Polignac number, because 20561603447 - 2⁶ = 20561603383 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20561603447.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20561603441) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1661579 + ... + 1673907.

It is an arithmetic number, because the mean of its divisors is an integer number (812300400).

Almost surely, 2^20561603447 is an apocalyptic number.

20561603447 is a deficient number, since it is larger than the sum of its proper divisors (5432009353).

20561603447 is a wasteful number, since it uses less digits than its factorization.

20561603447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12548 (or 12526 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 38.

The spelling of 20561603447 in words is "twenty billion, five hundred sixty-one million, six hundred three thousand, four hundred forty-seven".