1643633581856 has 192 divisors, whose sum is σ = 4042798905600. Its totient is φ = 641808728064.

The previous prime is 1643633581829. The next prime is 1643633581879. The reversal of 1643633581856 is 6581853363461.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 1643633581795 and 1643633581804.

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 31 ways as a sum of consecutive naturals, for example, 31694060 + ... + 31745876.

It is an arithmetic number, because the mean of its divisors is an integer number (21056244300).

Almost surely, 2^{1643633581856} is an apocalyptic number.

1643633581856 is a gapful number since it is divisible by the number (16) 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 1643633581856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2021399452800).

1643633581856 is an abundant number, since it is smaller than the sum of its proper divisors (2399165323744).

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

1643633581856 is a wasteful number, since it uses less digits than its factorization.

1643633581856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52139 (or 52131 counting only the distinct ones).

The product of its digits is 37324800, while the sum is 59.

The spelling of 1643633581856 in words is "one trillion, six hundred forty-three billion, six hundred thirty-three million, five hundred eighty-one thousand, eight hundred fifty-six".