643561536 has 28 divisors (see below), whose sum is σ = 1702757072. Its totient is φ = 214520448.

The previous prime is 643561517. The next prime is 643561549. The reversal of 643561536 is 635165346.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 643561494 and 643561503.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1675750 + ... + 1676133.

Almost surely, 2^643561536 is an apocalyptic number.

It is an amenable number.

643561536 is an abundant number, since it is smaller than the sum of its proper divisors (1059195536).

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

643561536 is a wasteful number, since it uses less digits than its factorization.

643561536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3351898 (or 3351888 counting only the distinct ones).

The product of its digits is 194400, while the sum is 39.

The square root of 643561536 is about 25368.5146589232. The cubic root of 643561536 is about 863.3694816817.

The spelling of 643561536 in words is "six hundred forty-three million, five hundred sixty-one thousand, five hundred thirty-six".