2005643640 has 512 divisors, whose sum is σ = 8244633600. Its totient is φ = 376842240.

The previous prime is 2005643621. The next prime is 2005643681. The reversal of 2005643640 is 463465002.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 2005643598 and 2005643607.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 7086939 + ... + 7087221.

It is an arithmetic number, because the mean of its divisors is an integer number (16102800).

Almost surely, 2^2005643640 is an apocalyptic number.

2005643640 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 2005643640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4122316800).

2005643640 is an abundant number, since it is smaller than the sum of its proper divisors (6238989960).

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

2005643640 is a wasteful number, since it uses less digits than its factorization.

2005643640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 387 (or 383 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 30.

The square root of 2005643640 is about 44784.4129134233. The cubic root of 2005643640 is about 1261.1050270744.

The spelling of 2005643640 in words is "two billion, five million, six hundred forty-three thousand, six hundred forty".