643755923 has 8 divisors (see below), whose sum is σ = 651054768. Its totient is φ = 636470784.

The previous prime is 643755919. The next prime is 643755941. The reversal of 643755923 is 329557346.

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

It is a cyclic number.

It is not a de Polignac number, because 643755923 - 2² = 643755919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643755913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 112940 + ... + 118502.

It is an arithmetic number, because the mean of its divisors is an integer number (81381846).

Almost surely, 2^643755923 is an apocalyptic number.

643755923 is a deficient number, since it is larger than the sum of its proper divisors (7298845).

643755923 is a wasteful number, since it uses less digits than its factorization.

643755923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6853.

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

The square root of 643755923 is about 25372.3456345684. The cubic root of 643755923 is about 863.4563995077.

The spelling of 643755923 in words is "six hundred forty-three million, seven hundred fifty-five thousand, nine hundred twenty-three".