643505 has 8 divisors (see below), whose sum is σ = 777600. Its totient is φ = 511216.

The previous prime is 643493. The next prime is 643507. The reversal of 643505 is 505346.

643505 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643505 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643507) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 536 + ... + 1254.

It is an arithmetic number, because the mean of its divisors is an integer number (97200).

2⁶⁴³⁵⁰⁵ is an apocalyptic number.

It is an amenable number.

643505 is a deficient number, since it is larger than the sum of its proper divisors (134095).

643505 is a wasteful number, since it uses less digits than its factorization.

643505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 903.

The product of its (nonzero) digits is 1800, while the sum is 23.

The square root of 643505 is about 802.1876339112. The cubic root of 643505 is about 86.3344198999.

The spelling of 643505 in words is "six hundred forty-three thousand, five hundred five".