4005665820 has 144 divisors (see below), whose sum is σ = 13141320192. Its totient is φ = 981780480.

The previous prime is 4005665791. The next prime is 4005665827. The reversal of 4005665820 is 285665004.

4005665820 is a `hidden beast` number, since 40 + 0 + 566 + 58 + 2 + 0 = 666.

4005665820 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4005665827) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 560389 + ... + 567491.

It is an arithmetic number, because the mean of its divisors is an integer number (91259168).

Almost surely, 2^4005665820 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 4005665820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (6570660096).

4005665820 is an abundant number, since it is smaller than the sum of its proper divisors (9135654372).

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

4005665820 is a wasteful number, since it uses less digits than its factorization.

4005665820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7372 (or 7367 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The square root of 4005665820 is about 63290.3295930745. The cubic root of 4005665820 is about 1588.1501924239.

The spelling of 4005665820 in words is "four billion, five million, six hundred sixty-five thousand, eight hundred twenty".