643756652 has 24 divisors (see below), whose sum is σ = 1404560640. Its totient is φ = 250814160.

The previous prime is 643756643. The next prime is 643756657. The reversal of 643756652 is 256657346.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is not an unprimeable number, because it can be changed into a prime (643756657) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 1044752 + ... + 1045367.

It is an arithmetic number, because the mean of its divisors is an integer number (58523360).

Almost surely, 2^643756652 is an apocalyptic number.

It is an amenable number.

643756652 is an abundant number, since it is smaller than the sum of its proper divisors (760803988).

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

643756652 is a wasteful number, since it uses less digits than its factorization.

643756652 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2090141 (or 2090139 counting only the distinct ones).

The product of its digits is 907200, while the sum is 44.

The square root of 643756652 is about 25372.3600005991. The cubic root of 643756652 is about 863.4567254384.

The spelling of 643756652 in words is "six hundred forty-three million, seven hundred fifty-six thousand, six hundred fifty-two".