21105665728992 has 240 divisors, whose sum is σ = 66862184214672. Its totient is φ = 6492467312640.

The previous prime is 21105665728897. The next prime is 21105665729023. The reversal of 21105665728992 is 29982756650112.

21105665728992 is a `hidden beast` number, since 2 + 1 + 1 + 0 + 56 + 6 + 572 + 8 + 9 + 9 + 2 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 142021767 + ... + 142170297.

Almost surely, 2^{21105665728992} 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 21105665728992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33431092107336).

21105665728992 is an abundant number, since it is smaller than the sum of its proper divisors (45756518485680).

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

21105665728992 is a wasteful number, since it uses less digits than its factorization.

21105665728992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152783 (or 152766 counting only the distinct ones).

The product of its (nonzero) digits is 32659200, while the sum is 63.

The spelling of 21105665728992 in words is "twenty-one trillion, one hundred five billion, six hundred sixty-five million, seven hundred twenty-eight thousand, nine hundred ninety-two".