646979840640 has 1536 divisors, whose sum is σ = 2879944704000. Its totient is φ = 135444234240.

The previous prime is 646979840629. The next prime is 646979840653. The reversal of 646979840640 is 46048979646.

646979840640 is a `hidden beast` number, since 6 + 469 + 7 + 98 + 40 + 6 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 641208456 + ... + 641209464.

It is an arithmetic number, because the mean of its divisors is an integer number (1874964000).

Almost surely, 2^646979840640 is an apocalyptic number.

646979840640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646979840640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1439972352000).

646979840640 is an abundant number, since it is smaller than the sum of its proper divisors (2232964863360).

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

646979840640 is a wasteful number, since it uses less digits than its factorization.

646979840640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1100 (or 1076 counting only the distinct ones).

The product of its (nonzero) digits is 62705664, while the sum is 63.

The spelling of 646979840640 in words is "six hundred forty-six billion, nine hundred seventy-nine million, eight hundred forty thousand, six hundred forty".