643221236 has 36 divisors (see below), whose sum is σ = 1312510500. Its totient is φ = 275014656.

The previous prime is 643221223. The next prime is 643221251. The reversal of 643221236 is 632122346.

It can be written as a sum of positive squares in 2 ways, for example, as 338928100 + 304293136 = 18410^2 + 17444^2 .

It is a junction number, because it is equal to n+sod(n) for n = 643221199 and 643221208.

It is a congruent number.

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, 84350 + ... + 91658.

It is an arithmetic number, because the mean of its divisors is an integer number (36458625).

Almost surely, 2^643221236 is an apocalyptic number.

It is an amenable number.

643221236 is an abundant number, since it is smaller than the sum of its proper divisors (669289264).

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

643221236 is a wasteful number, since it uses less digits than its factorization.

643221236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7776 (or 7767 counting only the distinct ones).

The product of its digits is 10368, while the sum is 29.

The square root of 643221236 is about 25361.8066391178. The cubic root of 643221236 is about 863.2172784507.

The spelling of 643221236 in words is "six hundred forty-three million, two hundred twenty-one thousand, two hundred thirty-six".