21685440001680 has 240 divisors, whose sum is σ = 89633152277760. Its totient is φ = 4575389524992.

The previous prime is 21685440001679. The next prime is 21685440001739. The reversal of 21685440001680 is 8610004458612.

It is a happy number.

21685440001680 is a `hidden beast` number, since 2 + 1 + 6 + 85 + 4 + 400 + 0 + 168 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

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

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 165421660 + ... + 165552699.

It is an arithmetic number, because the mean of its divisors is an integer number (373471467824).

Almost surely, 2^{21685440001680} is an apocalyptic number.

21685440001680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21685440001680 is an abundant number, since it is smaller than the sum of its proper divisors (67947712276080).

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

21685440001680 is a wasteful number, since it uses less digits than its factorization.

21685440001680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330974398 (or 330974389 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 45.

The spelling of 21685440001680 in words is "twenty-one trillion, six hundred eighty-five billion, four hundred forty million, one thousand, six hundred eighty".