643458836 has 6 divisors (see below), whose sum is σ = 1126052970. Its totient is φ = 321729416.

The previous prime is 643458817. The next prime is 643458839. The reversal of 643458836 is 638854346.

It can be written as a sum of positive squares in only one way, i.e., 474978436 + 168480400 = 21794^2 + 12980^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643458839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80432351 + ... + 80432358.

It is an arithmetic number, because the mean of its divisors is an integer number (187675495).

Almost surely, 2^643458836 is an apocalyptic number.

It is an amenable number.

643458836 is a deficient number, since it is larger than the sum of its proper divisors (482594134).

643458836 is a wasteful number, since it uses less digits than its factorization.

643458836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160864713 (or 160864711 counting only the distinct ones).

The product of its digits is 1658880, while the sum is 47.

The square root of 643458836 is about 25366.4904155068. The cubic root of 643458836 is about 863.3235535366.

The spelling of 643458836 in words is "six hundred forty-three million, four hundred fifty-eight thousand, eight hundred thirty-six".