643356 has 96 divisors (see below), whose sum is σ = 2042880. Its totient is φ = 171072.

The previous prime is 643303. The next prime is 643369. The reversal of 643356 is 653346.

643356 = 46² + 47² + ... + 126².

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

Its product of digits (6480) is a multiple of the sum of its prime divisors (72).

It is a congruent number.

It is an unprimeable number.

643356 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17370 + ... + 17406.

It is an arithmetic number, because the mean of its divisors is an integer number (21280).

2⁶⁴³³⁵⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643356, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1021440).

643356 is an abundant number, since it is smaller than the sum of its proper divisors (1399524).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

643356 is a wasteful number, since it uses less digits than its factorization.

643356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80 (or 72 counting only the distinct ones).

The product of its digits is 6480, while the sum is 27.

The square root of 643356 is about 802.0947574944. The cubic root of 643356 is about 86.3277559675.

It can be divided in two parts, 643 and 356, that added together give a palindrome (999).

The spelling of 643356 in words is "six hundred forty-three thousand, three hundred fifty-six".