646738129 has 2 divisors, whose sum is σ = 646738130. Its totient is φ = 646738128.

The previous prime is 646738121. The next prime is 646738177. The reversal of 646738129 is 921837646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 526243600 + 120494529 = 22940^2 + 10977^2 .

It is a cyclic number.

It is not a de Polignac number, because 646738129 - 2³ = 646738121 is a prime.

It is not a weakly prime, because it can be changed into another prime (646738121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323369064 + 323369065.

It is an arithmetic number, because the mean of its divisors is an integer number (323369065).

Almost surely, 2^646738129 is an apocalyptic number.

It is an amenable number.

646738129 is a deficient number, since it is larger than the sum of its proper divisors (1).

646738129 is an equidigital number, since it uses as much as digits as its factorization.

646738129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 435456, while the sum is 46.

The square root of 646738129 is about 25431.0465573086. The cubic root of 646738129 is about 864.7876694916.

The spelling of 646738129 in words is "six hundred forty-six million, seven hundred thirty-eight thousand, one hundred twenty-nine".