1643996528640 has 600 divisors, whose sum is σ = 5950540937880. Its totient is φ = 434185961472.

The previous prime is 1643996528617. The next prime is 1643996528641. The reversal of 1643996528640 is 468256993461.

1643996528640 is a `hidden beast` number, since 1 + 6 + 43 + 9 + 9 + 6 + 528 + 64 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 597516632064 + 1046479896576 = 772992^2 + 1022976^2 .

It is not an unprimeable number, because it can be changed into a prime (1643996528641) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 723270544 + ... + 723272816.

Almost surely, 2^{1643996528640} is an apocalyptic number.

1643996528640 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 1643996528640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2975270468940).

1643996528640 is an abundant number, since it is smaller than the sum of its proper divisors (4306544409240).

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

1643996528640 is an equidigital number, since it uses as much as digits as its factorization.

1643996528640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2427 (or 2392 counting only the distinct ones).

The product of its (nonzero) digits is 67184640, while the sum is 63.

The spelling of 1643996528640 in words is "one trillion, six hundred forty-three billion, nine hundred ninety-six million, five hundred twenty-eight thousand, six hundred forty".