643444129 has 2 divisors, whose sum is σ = 643444130. Its totient is φ = 643444128.

The previous prime is 643444121. The next prime is 643444181. The reversal of 643444129 is 921444346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 324000000 + 319444129 = 18000^2 + 17873^2 .

It is a cyclic number.

It is not a de Polignac number, because 643444129 - 2³ = 643444121 is a prime.

It is not a weakly prime, because it can be changed into another prime (643444121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321722064 + 321722065.

It is an arithmetic number, because the mean of its divisors is an integer number (321722065).

Almost surely, 2^643444129 is an apocalyptic number.

It is an amenable number.

643444129 is a deficient number, since it is larger than the sum of its proper divisors (1).

643444129 is an equidigital number, since it uses as much as digits as its factorization.

643444129 is an evil number, because the sum of its binary digits is even.

The product of its digits is 82944, while the sum is 37.

The square root of 643444129 is about 25366.2005235313. The cubic root of 643444129 is about 863.3169760652.

The spelling of 643444129 in words is "six hundred forty-three million, four hundred forty-four thousand, one hundred twenty-nine".