643902668368 has 20 divisors (see below), whose sum is σ = 1248750738900. Its totient is φ = 321644413184.

The previous prime is 643902668341. The next prime is 643902668407. The reversal of 643902668368 is 863866209346.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 463695626304 + 180207042064 = 680952^2 + 424508^2 .

It is a super-2 number, since 2×643902668368² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19165255 + ... + 19198822.

It is an arithmetic number, because the mean of its divisors is an integer number (62437536945).

Almost surely, 2^643902668368 is an apocalyptic number.

It is an amenable number.

643902668368 is a deficient number, since it is larger than the sum of its proper divisors (604848070532).

643902668368 is a wasteful number, since it uses less digits than its factorization.

643902668368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38365134 (or 38365128 counting only the distinct ones).

The product of its (nonzero) digits is 53747712, while the sum is 61.

The spelling of 643902668368 in words is "six hundred forty-three billion, nine hundred two million, six hundred sixty-eight thousand, three hundred sixty-eight".