643775436 has 36 divisors (see below), whose sum is σ = 1630893264. Its totient is φ = 214120800.

The previous prime is 643775413. The next prime is 643775453. The reversal of 643775436 is 634577346.

It is a tau number, because it is divible by the number of its divisors (36).

It is a junction number, because it is equal to n+sod(n) for n = 643775391 and 643775400.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2800 + ... + 35991.

Almost surely, 2^643775436 is an apocalyptic number.

It is an amenable number.

643775436 is an abundant number, since it is smaller than the sum of its proper divisors (987117828).

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

643775436 is a wasteful number, since it uses less digits than its factorization.

643775436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39262 (or 39257 counting only the distinct ones).

The product of its digits is 1270080, while the sum is 45.

The square root of 643775436 is about 25372.7301644896. The cubic root of 643775436 is about 863.4651235463.

The spelling of 643775436 in words is "six hundred forty-three million, seven hundred seventy-five thousand, four hundred thirty-six".