2005781840 has 80 divisors (see below), whose sum is σ = 4944207360. Its totient is φ = 755412480.

The previous prime is 2005781831. The next prime is 2005781849. The reversal of 2005781840 is 481875002.

It is an interprime number because it is at equal distance from previous prime (2005781831) and next prime (2005781849).

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 2005781840.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2005781849) 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 15 ways as a sum of consecutive naturals, for example, 80831 + ... + 102689.

It is an arithmetic number, because the mean of its divisors is an integer number (61802592).

Almost surely, 2^2005781840 is an apocalyptic number.

2005781840 is a gapful number since it is divisible by the number (20) 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 2005781840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2472103680).

2005781840 is an abundant number, since it is smaller than the sum of its proper divisors (2938425520).

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

2005781840 is a wasteful number, since it uses less digits than its factorization.

2005781840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21940 (or 21934 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 35.

The square root of 2005781840 is about 44785.9558343908. The cubic root of 2005781840 is about 1261.1339921256.

The spelling of 2005781840 in words is "two billion, five million, seven hundred eighty-one thousand, eight hundred forty".