645643 has 8 divisors (see below), whose sum is σ = 690768. Its totient is φ = 601344.

The previous prime is 645641. The next prime is 645647. The reversal of 645643 is 346546.

645643 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 not a de Polignac number, because 645643 - 2¹ = 645641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645641) 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, 2655 + ... + 2887.

It is an arithmetic number, because the mean of its divisors is an integer number (86346).

2⁶⁴⁵⁶⁴³ is an apocalyptic number.

645643 is a deficient number, since it is larger than the sum of its proper divisors (45125).

645643 is a wasteful number, since it uses less digits than its factorization.

645643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 413.

The product of its digits is 8640, while the sum is 28.

The square root of 645643 is about 803.5191348064. The cubic root of 645643 is about 86.4299275468.

The spelling of 645643 in words is "six hundred forty-five thousand, six hundred forty-three".