1986643591680 has 960 divisors, whose sum is σ = 7241386521600. Its totient is φ = 463966863360.

The previous prime is 1986643591679. The next prime is 1986643591687. The reversal of 1986643591680 is 861953466891.

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

It is a Harshad number since it is a multiple of its sum of digits (66).

It is not an unprimeable number, because it can be changed into a prime (1986643591687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 3316600021 + ... + 3316600619.

It is an arithmetic number, because the mean of its divisors is an integer number (7543110960).

Almost surely, 2^{1986643591680} is an apocalyptic number.

1986643591680 is a gapful number since it is divisible by the number (10) 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 1986643591680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3620693260800).

1986643591680 is an abundant number, since it is smaller than the sum of its proper divisors (5254742929920).

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

1986643591680 is a wasteful number, since it uses less digits than its factorization.

1986643591680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 773 (or 746 counting only the distinct ones).

The product of its (nonzero) digits is 67184640, while the sum is 66.

The spelling of 1986643591680 in words is "one trillion, nine hundred eighty-six billion, six hundred forty-three million, five hundred ninety-one thousand, six hundred eighty".