21081508208640 has 2240 divisors, whose sum is σ = 86058552710592. Its totient is φ = 4892236185600.

The previous prime is 21081508208639. The next prime is 21081508208653. The reversal of 21081508208640 is 4680280518012.

21081508208640 is a `hidden beast` number, since 2 + 1 + 0 + 8 + 1 + 508 + 20 + 86 + 40 = 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 pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 109230612384 + ... + 109230612576.

Almost surely, 2^{21081508208640} is an apocalyptic number.

21081508208640 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 21081508208640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43029276355296).

21081508208640 is an abundant number, since it is smaller than the sum of its proper divisors (64977044501952).

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

21081508208640 is a wasteful number, since it uses less digits than its factorization.

21081508208640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361 (or 328 counting only the distinct ones).

The product of its (nonzero) digits is 245760, while the sum is 45.

The spelling of 21081508208640 in words is "twenty-one trillion, eighty-one billion, five hundred eight million, two hundred eight thousand, six hundred forty".