21144694688640 has 1792 divisors, whose sum is σ = 86460336230400. Its totient is φ = 4911107604480.

The previous prime is 21144694688639. The next prime is 21144694688681. The reversal of 21144694688640 is 4688649644112.

21144694688640 is a `hidden beast` number, since 2 + 1 + 1 + 446 + 94 + 68 + 8 + 6 + 40 = 666.

It is a super-2 number, since 2×21144694688640² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 223 ways as a sum of consecutive naturals, for example, 5655171891 + ... + 5655175629.

Almost surely, 2^{21144694688640} is an apocalyptic number.

21144694688640 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 21144694688640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43230168115200).

21144694688640 is an abundant number, since it is smaller than the sum of its proper divisors (65315641541760).

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

21144694688640 is a wasteful number, since it uses less digits than its factorization.

21144694688640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3847 (or 3820 counting only the distinct ones).

The product of its (nonzero) digits is 63700992, while the sum is 63.

The spelling of 21144694688640 in words is "twenty-one trillion, one hundred forty-four billion, six hundred ninety-four million, six hundred eighty-eight thousand, six hundred forty".