2001643840 has 56 divisors (see below), whose sum is σ = 5447336832. Its totient is φ = 686277120.

The previous prime is 2001643823. The next prime is 2001643859. The reversal of 2001643840 is 483461002.

It is a tau number, because it is divible by the number of its divisors (56).

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 2001643799 and 2001643808.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 444556 + ... + 449035.

It is an arithmetic number, because the mean of its divisors is an integer number (97273872).

Almost surely, 2^2001643840 is an apocalyptic number.

2001643840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2001643840 is an abundant number, since it is smaller than the sum of its proper divisors (3445692992).

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

2001643840 is an equidigital number, since it uses as much as digits as its factorization.

2001643840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 893615 (or 893605 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 2001643840 is about 44739.7344650144. The cubic root of 2001643840 is about 1260.2661401364.

The spelling of 2001643840 in words is "two billion, one million, six hundred forty-three thousand, eight hundred forty".