1643559660 has 336 divisors, whose sum is σ = 5784156000. Its totient is φ = 389670912.

The previous prime is 1643559613. The next prime is 1643559683. The reversal of 1643559660 is 669553461.

1643559660 is a `hidden beast` number, since 16 + 43 + 5 + 596 + 6 + 0 = 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 111 ways as a sum of consecutive naturals, for example, 4709166 + ... + 4709514.

It is an arithmetic number, because the mean of its divisors is an integer number (17214750).

Almost surely, 2^1643559660 is an apocalyptic number.

1643559660 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 1643559660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2892078000).

1643559660 is an abundant number, since it is smaller than the sum of its proper divisors (4140596340).

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

1643559660 is a wasteful number, since it uses less digits than its factorization.

1643559660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412 (or 395 counting only the distinct ones).

The product of its (nonzero) digits is 583200, while the sum is 45.

The square root of 1643559660 is about 40540.8394091686. The cubic root of 1643559660 is about 1180.1263055454.

The spelling of 1643559660 in words is "one billion, six hundred forty-three million, five hundred fifty-nine thousand, six hundred sixty".