20561353826816 has 80 divisors (see below), whose sum is σ = 44822695012128. Its totient is φ = 9344950272000.

The previous prime is 20561353826807. The next prime is 20561353826821. The reversal of 20561353826816 is 61862835316502.

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, 47730791 + ... + 48159641.

Almost surely, 2^{20561353826816} 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 20561353826816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22411347506064).

20561353826816 is an abundant number, since it is smaller than the sum of its proper divisors (24261341185312).

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

20561353826816 is an equidigital number, since it uses as much as digits as its factorization.

20561353826816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 437393 (or 437377 counting only the distinct ones).

The product of its (nonzero) digits is 12441600, while the sum is 56.

The spelling of 20561353826816 in words is "twenty trillion, five hundred sixty-one billion, three hundred fifty-three million, eight hundred twenty-six thousand, eight hundred sixteen".