643280920 has 32 divisors (see below), whose sum is σ = 1448136720. Its totient is φ = 257178240.

The previous prime is 643280917. The next prime is 643280921. The reversal of 643280920 is 29082346.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643280921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 116134 + ... + 121546.

Almost surely, 2^643280920 is an apocalyptic number.

It is an amenable number.

643280920 is an abundant number, since it is smaller than the sum of its proper divisors (804855800).

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

643280920 is a wasteful number, since it uses less digits than its factorization.

643280920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8395 (or 8391 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 34.

The square root of 643280920 is about 25362.9832630154. The cubic root of 643280920 is about 863.2439767123.

The spelling of 643280920 in words is "six hundred forty-three million, two hundred eighty thousand, nine hundred twenty".