21663223649550 has 960 divisors, whose sum is σ = 71083814630400. Its totient is φ = 4789928908800.

The previous prime is 21663223649549. The next prime is 21663223649563. The reversal of 21663223649550 is 5594632236612.

21663223649550 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 3 + 2 + 23 + 64 + 9 + 550 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 479 ways as a sum of consecutive naturals, for example, 55689520756 + ... + 55689521144.

It is an arithmetic number, because the mean of its divisors is an integer number (74045640240).

Almost surely, 2^{21663223649550} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21663223649550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35541907315200).

21663223649550 is an abundant number, since it is smaller than the sum of its proper divisors (49420590980850).

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

21663223649550 is a wasteful number, since it uses less digits than its factorization.

21663223649550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 943 (or 929 counting only the distinct ones).

The product of its (nonzero) digits is 13996800, while the sum is 54.

The spelling of 21663223649550 in words is "twenty-one trillion, six hundred sixty-three billion, two hundred twenty-three million, six hundred forty-nine thousand, five hundred fifty".