21645277205760 has 864 divisors, whose sum is σ = 81568265670528. Its totient is φ = 5267833159680.

The previous prime is 21645277205759. The next prime is 21645277205771. The reversal of 21645277205760 is 6750277254612.

21645277205760 is a `hidden beast` number, since 2 + 1 + 6 + 4 + 527 + 7 + 2 + 0 + 57 + 60 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21645277205697 and 21645277205706.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4961097339 + ... + 4961101701.

Almost surely, 2^{21645277205760} is an apocalyptic number.

21645277205760 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 21645277205760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40784132835264).

21645277205760 is an abundant number, since it is smaller than the sum of its proper divisors (59922988464768).

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

21645277205760 is a wasteful number, since it uses less digits than its factorization.

21645277205760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4771 (or 4754 counting only the distinct ones).

The product of its (nonzero) digits is 9878400, while the sum is 54.

The spelling of 21645277205760 in words is "twenty-one trillion, six hundred forty-five billion, two hundred seventy-seven million, two hundred five thousand, seven hundred sixty".