646244864 has 40 divisors (see below), whose sum is σ = 1304116308. Its totient is φ = 319897600.

The previous prime is 646244861. The next prime is 646244873. The reversal of 646244864 is 468442646.

It can be written as a sum of positive squares in 2 ways, for example, as 586027264 + 60217600 = 24208^2 + 7760^2 .

It is not an unprimeable number, because it can be changed into a prime (646244861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45464 + ... + 57960.

Almost surely, 2^646244864 is an apocalyptic number.

646244864 is a gapful number since it is divisible by the number (64) 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 646244864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (652058154).

646244864 is an abundant number, since it is smaller than the sum of its proper divisors (657871444).

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

646244864 is a wasteful number, since it uses less digits than its factorization.

646244864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12616 (or 12600 counting only the distinct ones).

The product of its digits is 884736, while the sum is 44.

The square root of 646244864 is about 25421.3466205077. The cubic root of 646244864 is about 864.5677566890.

The spelling of 646244864 in words is "six hundred forty-six million, two hundred forty-four thousand, eight hundred sixty-four".