39643 has 4 divisors (see below), whose sum is σ = 41040. Its totient is φ = 38248.

The previous prime is 39631. The next prime is 39659. The reversal of 39643 is 34693.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-39643 is a prime.

It is a Duffinian number.

39643 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39623) 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, 655 + ... + 712.

It is an arithmetic number, because the mean of its divisors is an integer number (10260).

2³⁹⁶⁴³ is an apocalyptic number.

39643 is a deficient number, since it is larger than the sum of its proper divisors (1397).

39643 is a wasteful number, since it uses less digits than its factorization.

39643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1396.

The product of its digits is 1944, while the sum is 25.

The square root of 39643 is about 199.1054996729. The cubic root of 39643 is about 34.0974711678.

Subtracting from 39643 its reverse (34693), we obtain a triangular number (4950 = T₉₉).

The spelling of 39643 in words is "thirty-nine thousand, six hundred forty-three".