643923755 has 16 divisors (see below), whose sum is σ = 812125440. Its totient is φ = 489184608.

The previous prime is 643923727. The next prime is 643923757. The reversal of 643923755 is 557329346.

It is not a de Polignac number, because 643923755 - 2⁸ = 643923499 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643923757) 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 15 ways as a sum of consecutive naturals, for example, 4157 + ... + 36126.

It is an arithmetic number, because the mean of its divisors is an integer number (50757840).

Almost surely, 2^643923755 is an apocalyptic number.

643923755 is a deficient number, since it is larger than the sum of its proper divisors (168201685).

643923755 is a wasteful number, since it uses less digits than its factorization.

643923755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40450.

The product of its digits is 680400, while the sum is 44.

The square root of 643923755 is about 25375.6527994848. The cubic root of 643923755 is about 863.5314295088.

The spelling of 643923755 in words is "six hundred forty-three million, nine hundred twenty-three thousand, seven hundred fifty-five".