21366013904640 has 1080 divisors, whose sum is σ = 80336513759040. Its totient is φ = 5415604862976.

The previous prime is 21366013904633. The next prime is 21366013904663. The reversal of 21366013904640 is 4640931066312.

21366013904640 is a `hidden beast` number, since 2 + 1 + 3 + 6 + 601 + 39 + 0 + 4 + 6 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1080).

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 119 ways as a sum of consecutive naturals, for example, 13497165289 + ... + 13497166871.

It is an arithmetic number, because the mean of its divisors is an integer number (74385660888).

Almost surely, 2^{21366013904640} is an apocalyptic number.

21366013904640 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 21366013904640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40168256879520).

21366013904640 is an abundant number, since it is smaller than the sum of its proper divisors (58970499854400).

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

21366013904640 is an equidigital number, since it uses as much as digits as its factorization.

21366013904640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1779 (or 1689 counting only the distinct ones).

The product of its (nonzero) digits is 559872, while the sum is 45.

The spelling of 21366013904640 in words is "twenty-one trillion, three hundred sixty-six billion, thirteen million, nine hundred four thousand, six hundred forty".