643564 has 12 divisors (see below), whose sum is σ = 1132488. Its totient is φ = 320000.

The previous prime is 643553. The next prime is 643567. The reversal of 643564 is 465346.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (643567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 684 + ... + 1324.

It is an arithmetic number, because the mean of its divisors is an integer number (94374).

2⁶⁴³⁵⁶⁴ is an apocalyptic number.

It is an amenable number.

643564 is a deficient number, since it is larger than the sum of its proper divisors (488924).

643564 is a wasteful number, since it uses less digits than its factorization.

643564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 896 (or 894 counting only the distinct ones).

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

The square root of 643564 is about 802.2244075070. The cubic root of 643564 is about 86.3370583539.

The spelling of 643564 in words is "six hundred forty-three thousand, five hundred sixty-four".