643531648 has 16 divisors (see below), whose sum is σ = 1282035960. Its totient is φ = 321765760.

The previous prime is 643531633. The next prime is 643531667. The reversal of 643531648 is 846135346.

It is a tau number, because it is divible by the number of its divisors (16).

It is a self number, because there is not a number n which added to its sum of digits gives 643531648.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2513668 + ... + 2513923.

Almost surely, 2^643531648 is an apocalyptic number.

It is an amenable number.

643531648 is a deficient number, since it is larger than the sum of its proper divisors (638504312).

643531648 is an equidigital number, since it uses as much as digits as its factorization.

643531648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5027605 (or 5027593 counting only the distinct ones).

The product of its digits is 207360, while the sum is 40.

The square root of 643531648 is about 25367.9255754191. The cubic root of 643531648 is about 863.3561160670.

It can be divided in two parts, 6435 and 31648, that added together give a palindrome (38083).

The spelling of 643531648 in words is "six hundred forty-three million, five hundred thirty-one thousand, six hundred forty-eight".