643256 has 8 divisors (see below), whose sum is σ = 1206120. Its totient is φ = 321624.

The previous prime is 643243. The next prime is 643273. The reversal of 643256 is 652346.

It is a tau number, because it is divible by the number of its divisors (8).

It is a d-powerful number, because it can be written as 6⁷ + 4⁵ + 2¹¹ + 3⁷ + 5⁷ + 6⁷ .

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643256.

It is an unprimeable number.

643256 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 as a sum of consecutive naturals, namely, 40196 + ... + 40211.

It is an arithmetic number, because the mean of its divisors is an integer number (150765).

2⁶⁴³²⁵⁶ is an apocalyptic number.

It is an amenable number.

643256 is a deficient number, since it is larger than the sum of its proper divisors (562864).

643256 is a wasteful number, since it uses less digits than its factorization.

643256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80413 (or 80409 counting only the distinct ones).

The product of its digits is 4320, while the sum is 26.

The square root of 643256 is about 802.0324182974. The cubic root of 643256 is about 86.3232829526.

The spelling of 643256 in words is "six hundred forty-three thousand, two hundred fifty-six".