646824761856 has 360 divisors, whose sum is σ = 2338614201924. Its totient is φ = 170590371840.

The previous prime is 646824761831. The next prime is 646824761873. The reversal of 646824761856 is 658167428646.

It is a happy number.

646824761856 is a `hidden beast` number, since 6 + 4 + 6 + 8 + 2 + 4 + 7 + 618 + 5 + 6 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 631452729600 + 15372032256 = 794640^2 + 123984^2 .

It is a super-2 number, since 2×646824761856² (a number of 24 digits) contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 646824761793 and 646824761802.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2825116 + ... + 3045476.

Almost surely, 2^646824761856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646824761856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1169307100962).

646824761856 is an abundant number, since it is smaller than the sum of its proper divisors (1691789440068).

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

646824761856 is a wasteful number, since it uses less digits than its factorization.

646824761856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220412 (or 220386 counting only the distinct ones).

The product of its digits is 92897280, while the sum is 63.

The spelling of 646824761856 in words is "six hundred forty-six billion, eight hundred twenty-four million, seven hundred sixty-one thousand, eight hundred fifty-six".