643544257 has 8 divisors (see below), whose sum is σ = 661044096. Its totient is φ = 626203152.

The previous prime is 643544227. The next prime is 643544263. The reversal of 643544257 is 752445346.

643544257 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 643544257 - 2¹¹ = 643542209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643544207) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31443 + ... + 47704.

It is an arithmetic number, because the mean of its divisors is an integer number (82630512).

Almost surely, 2^643544257 is an apocalyptic number.

It is an amenable number.

643544257 is a deficient number, since it is larger than the sum of its proper divisors (17499839).

643544257 is a wasteful number, since it uses less digits than its factorization.

643544257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79367.

The product of its digits is 403200, while the sum is 40.

The square root of 643544257 is about 25368.1740966905. The cubic root of 643544257 is about 863.3617547362.

The spelling of 643544257 in words is "six hundred forty-three million, five hundred forty-four thousand, two hundred fifty-seven".