643405888 has 14 divisors (see below), whose sum is σ = 1276758686. Its totient is φ = 321702912.

The previous prime is 643405883. The next prime is 643405901. The reversal of 643405888 is 888504346.

It can be written as a sum of positive squares in only one way, i.e., 403527744 + 239878144 = 20088^2 + 15488^2 .

It is a super-2 number, since 2×643405888² = 827942273426137088, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (643405883) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5026545 + ... + 5026672.

It is an arithmetic number, because the mean of its divisors is an integer number (91197049).

Almost surely, 2^643405888 is an apocalyptic number.

It is an amenable number.

643405888 is a deficient number, since it is larger than the sum of its proper divisors (633352798).

643405888 is a wasteful number, since it uses less digits than its factorization.

643405888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10053229 (or 10053219 counting only the distinct ones).

The product of its (nonzero) digits is 737280, while the sum is 46.

The square root of 643405888 is about 25365.4467336966. The cubic root of 643405888 is about 863.2998729183.

The spelling of 643405888 in words is "six hundred forty-three million, four hundred five thousand, eight hundred eighty-eight".