643643129 has 4 divisors (see below), whose sum is σ = 645039780. Its totient is φ = 642246480.

The previous prime is 643643123. The next prime is 643643131. The reversal of 643643129 is 921346346.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 386201104 + 257442025 = 19652^2 + 16045^2 .

It is a cyclic number.

It is not a de Polignac number, because 643643129 - 2⁴ = 643643113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643643092 and 643643101.

It is not an unprimeable number, because it can be changed into a prime (643643123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 697634 + ... + 698555.

It is an arithmetic number, because the mean of its divisors is an integer number (161259945).

Almost surely, 2^643643129 is an apocalyptic number.

It is an amenable number.

643643129 is a deficient number, since it is larger than the sum of its proper divisors (1396651).

643643129 is a wasteful number, since it uses less digits than its factorization.

643643129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1396650.

The product of its digits is 93312, while the sum is 38.

The square root of 643643129 is about 25370.1227628090. The cubic root of 643643129 is about 863.4059671485.

The spelling of 643643129 in words is "six hundred forty-three million, six hundred forty-three thousand, one hundred twenty-nine".