643636956077 has 2 divisors, whose sum is σ = 643636956078. Its totient is φ = 643636956076.

The previous prime is 643636956041. The next prime is 643636956097. The reversal of 643636956077 is 770659636346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 438553870756 + 205083085321 = 662234^2 + 452861^2 .

It is a cyclic number.

It is not a de Polignac number, because 643636956077 - 2⁶ = 643636956013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643636956097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321818478038 + 321818478039.

It is an arithmetic number, because the mean of its divisors is an integer number (321818478039).

Almost surely, 2^643636956077 is an apocalyptic number.

It is an amenable number.

643636956077 is a deficient number, since it is larger than the sum of its proper divisors (1).

643636956077 is an equidigital number, since it uses as much as digits as its factorization.

643636956077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 102876480, while the sum is 62.

The spelling of 643636956077 in words is "six hundred forty-three billion, six hundred thirty-six million, nine hundred fifty-six thousand, seventy-seven".