643665280556 has 6 divisors (see below), whose sum is σ = 1126414240980. Its totient is φ = 321832640276.

The previous prime is 643665280523. The next prime is 643665280591. The reversal of 643665280556 is 655082566346.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80458160066 + ... + 80458160073.

It is an arithmetic number, because the mean of its divisors is an integer number (187735706830).

Almost surely, 2^643665280556 is an apocalyptic number.

It is an amenable number.

643665280556 is a deficient number, since it is larger than the sum of its proper divisors (482748960424).

643665280556 is a wasteful number, since it uses less digits than its factorization.

643665280556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160916320143 (or 160916320141 counting only the distinct ones).

The product of its (nonzero) digits is 31104000, while the sum is 56.

The spelling of 643665280556 in words is "six hundred forty-three billion, six hundred sixty-five million, two hundred eighty thousand, five hundred fifty-six".