21668619994560 has 1792 divisors, whose sum is σ = 98767232040960. Its totient is φ = 4340127744000.

The previous prime is 21668619994559. The next prime is 21668619994597. The reversal of 21668619994560 is 6549991686612.

21668619994560 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 86 + 1 + 9 + 99 + 456 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 5589015342 + ... + 5589019218.

It is an arithmetic number, because the mean of its divisors is an integer number (55115642880).

Almost surely, 2^{21668619994560} is an apocalyptic number.

21668619994560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21668619994560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49383616020480).

21668619994560 is an abundant number, since it is smaller than the sum of its proper divisors (77098612046400).

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

21668619994560 is a wasteful number, since it uses less digits than its factorization.

21668619994560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4223 (or 4207 counting only the distinct ones).

The product of its (nonzero) digits is 302330880, while the sum is 72.

The spelling of 21668619994560 in words is "twenty-one trillion, six hundred sixty-eight billion, six hundred nineteen million, nine hundred ninety-four thousand, five hundred sixty".