2005643 has 4 divisors (see below), whose sum is σ = 2123640. Its totient is φ = 1887648.

The previous prime is 2005613. The next prime is 2005667. The reversal of 2005643 is 3465002.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3465002 = 2 ⋅1732501.

It is a cyclic number.

It is not a de Polignac number, because 2005643 - 2⁶ = 2005579 is a prime.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (2005613) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58973 + ... + 59006.

It is an arithmetic number, because the mean of its divisors is an integer number (530910).

2^2005643 is an apocalyptic number.

2005643 is a deficient number, since it is larger than the sum of its proper divisors (117997).

2005643 is a wasteful number, since it uses less digits than its factorization.

2005643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117996.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 2005643 is about 1416.2072588431. The cubic root of 2005643 is about 126.1104892935.

The spelling of 2005643 in words is "two million, five thousand, six hundred forty-three".