646129128864 has 96 divisors (see below), whose sum is σ = 1785551040000. Its totient is φ = 204018580224.

The previous prime is 646129128839. The next prime is 646129128871. The reversal of 646129128864 is 468821921646.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (57).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27601837 + ... + 27625235.

It is an arithmetic number, because the mean of its divisors is an integer number (18599490000).

Almost surely, 2^646129128864 is an apocalyptic number.

It is an amenable number.

646129128864 is an abundant number, since it is smaller than the sum of its proper divisors (1139421911136).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

646129128864 is a wasteful number, since it uses less digits than its factorization.

646129128864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38570 (or 38562 counting only the distinct ones).

The product of its digits is 7962624, while the sum is 57.

The spelling of 646129128864 in words is "six hundred forty-six billion, one hundred twenty-nine million, one hundred twenty-eight thousand, eight hundred sixty-four".