21663561260550 has 384 divisors, whose sum is σ = 61819409018880. Its totient is φ = 4969201600000.

The previous prime is 21663561260531. The next prime is 21663561260623. The reversal of 21663561260550 is 5506216536612.

It is a self number, because there is not a number n which added to its sum of digits gives 21663561260550.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 6205544305 + ... + 6205547795.

It is an arithmetic number, because the mean of its divisors is an integer number (160988044320).

Almost surely, 2^{21663561260550} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21663561260550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30909704509440).

21663561260550 is an abundant number, since it is smaller than the sum of its proper divisors (40155847758330).

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

21663561260550 is a wasteful number, since it uses less digits than its factorization.

21663561260550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5260 (or 5255 counting only the distinct ones).

The product of its (nonzero) digits is 1944000, while the sum is 48.

The spelling of 21663561260550 in words is "twenty-one trillion, six hundred sixty-three billion, five hundred sixty-one million, two hundred sixty thousand, five hundred fifty".