643438 has 8 divisors (see below), whose sum is σ = 968688. Its totient is φ = 320544.

The previous prime is 643429. The next prime is 643439. The reversal of 643438 is 834346.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643439) by changing a digit.

643438 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 495 + ... + 1237.

It is an arithmetic number, because the mean of its divisors is an integer number (121086).

2⁶⁴³⁴³⁸ is an apocalyptic number.

643438 is a deficient number, since it is larger than the sum of its proper divisors (325250).

643438 is a wasteful number, since it uses less digits than its factorization.

643438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1178.

The product of its digits is 6912, while the sum is 28.

The square root of 643438 is about 802.1458720208. The cubic root of 643438 is about 86.3314234938.

It can be divided in two parts, 643 and 438, that added together give a triangular number (1081 = T₄₆).

The spelling of 643438 in words is "six hundred forty-three thousand, four hundred thirty-eight".