20561632056 has 192 divisors, whose sum is σ = 70349536800. Its totient is φ = 5529129984.

The previous prime is 20561632031. The next prime is 20561632057. The reversal of 20561632056 is 65023616502.

It is a happy number.

20561632056 is a `hidden beast` number, since 2 + 0 + 5 + 616 + 32 + 0 + 5 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 20561632056.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20561632057) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 122790 + ... + 237066.

Almost surely, 2^20561632056 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20561632056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35174768400).

20561632056 is an abundant number, since it is smaller than the sum of its proper divisors (49787904744).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20561632056 is a wasteful number, since it uses less digits than its factorization.

20561632056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114323 (or 114306 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

The spelling of 20561632056 in words is "twenty billion, five hundred sixty-one million, six hundred thirty-two thousand, fifty-six".