643617765 has 128 divisors (see below), whose sum is σ = 1370603520. Its totient is φ = 280433664.

The previous prime is 643617749. The next prime is 643617781. The reversal of 643617765 is 567716346.

It is an interprime number because it is at equal distance from previous prime (643617749) and next prime (643617781).

It is not a de Polignac number, because 643617765 - 2⁴ = 643617749 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 643617765.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1909677 + ... + 1910013.

It is an arithmetic number, because the mean of its divisors is an integer number (10707840).

Almost surely, 2^643617765 is an apocalyptic number.

It is an amenable number.

643617765 is an abundant number, since it is smaller than the sum of its proper divisors (726985755).

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

643617765 is a wasteful number, since it uses less digits than its factorization.

643617765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 448 (or 442 counting only the distinct ones).

The product of its digits is 635040, while the sum is 45.

The square root of 643617765 is about 25369.6228785530. The cubic root of 643617765 is about 863.3946256066.

The spelling of 643617765 in words is "six hundred forty-three million, six hundred seventeen thousand, seven hundred sixty-five".