21785405760 has 448 divisors, whose sum is σ = 79728364800. Its totient is φ = 5595955200.

The previous prime is 21785405743. The next prime is 21785405783. The reversal of 21785405760 is 6750458712.

21785405760 is a `hidden beast` number, since 2 + 1 + 78 + 5 + 4 + 0 + 576 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 31527015 + ... + 31527705.

It is an arithmetic number, because the mean of its divisors is an integer number (177965100).

Almost surely, 2^21785405760 is an apocalyptic number.

21785405760 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 21785405760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39864182400).

21785405760 is an abundant number, since it is smaller than the sum of its proper divisors (57942959040).

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

21785405760 is a wasteful number, since it uses less digits than its factorization.

21785405760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 847 (or 831 counting only the distinct ones).

The product of its (nonzero) digits is 470400, while the sum is 45.

The spelling of 21785405760 in words is "twenty-one billion, seven hundred eighty-five million, four hundred five thousand, seven hundred sixty".