643766 has 8 divisors (see below), whose sum is σ = 969240. Its totient is φ = 320688.

The previous prime is 643751. The next prime is 643781. The reversal of 643766 is 667346.

It is an interprime number because it is at equal distance from previous prime (643751) and next prime (643781).

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

It is a congruent number.

It is an unprimeable number.

643766 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, 425 + ... + 1211.

It is an arithmetic number, because the mean of its divisors is an integer number (121155).

2⁶⁴³⁷⁶⁶ is an apocalyptic number.

643766 is a deficient number, since it is larger than the sum of its proper divisors (325474).

643766 is a wasteful number, since it uses less digits than its factorization.

643766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1198.

The product of its digits is 18144, while the sum is 32.

The square root of 643766 is about 802.3502975634. The cubic root of 643766 is about 86.3460904841.

The spelling of 643766 in words is "six hundred forty-three thousand, seven hundred sixty-six".