21785973995520 has 960 divisors, whose sum is σ = 89350734432960. Its totient is φ = 4973646053376.

The previous prime is 21785973995507. The next prime is 21785973995549. The reversal of 21785973995520 is 2559937958712.

21785973995520 is a `hidden beast` number, since 2 + 1 + 7 + 8 + 5 + 9 + 7 + 3 + 9 + 95 + 520 = 666.

It is a tau number, because it is divible by the number of its divisors (960).

It is a Smith number, since the sum of its digits (72) coincides with the sum of the digits of its prime factors.

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 pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 6346043724 + ... + 6346047156.

It is an arithmetic number, because the mean of its divisors is an integer number (93073681701).

Almost surely, 2^{21785973995520} is an apocalyptic number.

21785973995520 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 21785973995520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44675367216480).

21785973995520 is an abundant number, since it is smaller than the sum of its proper divisors (67564760437440).

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

21785973995520 is a wasteful number, since it uses less digits than its factorization.

21785973995520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4572 (or 4543 counting only the distinct ones).

The product of its (nonzero) digits is 428652000, while the sum is 72.

The spelling of 21785973995520 in words is "twenty-one trillion, seven hundred eighty-five billion, nine hundred seventy-three million, nine hundred ninety-five thousand, five hundred twenty".