643769 has 4 divisors (see below), whose sum is σ = 735744. Its totient is φ = 551796.

The previous prime is 643751. The next prime is 643781. The reversal of 643769 is 967346.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a de Polignac number, because none of the positive numbers 2^k-643769 is a prime.

It is a super-2 number, since 2×643769² = 828877050722, which contains 22 as substring.

It is a d-powerful number, because it can be written as 6 + 4⁸ + 7² + 3¹² + 6⁶ + 9² .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643729) 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, 45977 + ... + 45990.

It is an arithmetic number, because the mean of its divisors is an integer number (183936).

2⁶⁴³⁷⁶⁹ is an apocalyptic number.

It is an amenable number.

643769 is a deficient number, since it is larger than the sum of its proper divisors (91975).

643769 is an equidigital number, since it uses as much as digits as its factorization.

643769 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91974.

The product of its digits is 27216, while the sum is 35.

The square root of 643769 is about 802.3521670688. The cubic root of 643769 is about 86.3462246104.

It can be divided in two parts, 6437 and 69, that multiplied together give a triangular number (444153 = T₉₄₂).

The spelling of 643769 in words is "six hundred forty-three thousand, seven hundred sixty-nine".