646819128 has 256 divisors, whose sum is σ = 2045952000. Its totient is φ = 188116992.

The previous prime is 646819127. The next prime is 646819141. The reversal of 646819128 is 821918646.

646819128 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646819127) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5093001 + ... + 5093127.

It is an arithmetic number, because the mean of its divisors is an integer number (7992000).

Almost surely, 2^646819128 is an apocalyptic number.

646819128 is a gapful number since it is divisible by the number (68) 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 646819128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1022976000).

646819128 is an abundant number, since it is smaller than the sum of its proper divisors (1399132872).

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

646819128 is a wasteful number, since it uses less digits than its factorization.

646819128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251 (or 241 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The square root of 646819128 is about 25432.6390294047. The cubic root of 646819128 is about 864.8237706631.

The spelling of 646819128 in words is "six hundred forty-six million, eight hundred nineteen thousand, one hundred twenty-eight".