643642666506356 has 24 divisors (see below), whose sum is σ = 1293444592980960. Its totient is φ = 277166698495200.

The previous prime is 643642666506331. The next prime is 643642666506373. The reversal of 643642666506356 is 653605666246346.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 384953747075 + ... + 384953748746.

It is an arithmetic number, because the mean of its divisors is an integer number (53893524707540).

Almost surely, 2^{643642666506356} is an apocalyptic number.

It is an amenable number.

643642666506356 is an abundant number, since it is smaller than the sum of its proper divisors (649801926474604).

643642666506356 is a wasteful number, since it uses less digits than its factorization.

643642666506356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769907495855 (or 769907495853 counting only the distinct ones).

The product of its (nonzero) digits is 2015539200, while the sum is 68.

The spelling of 643642666506356 in words is "six hundred forty-three trillion, six hundred forty-two billion, six hundred sixty-six million, five hundred six thousand, three hundred fifty-six".