643797820 has 48 divisors (see below), whose sum is σ = 1439067168. Its totient is φ = 241090560.

The previous prime is 643797799. The next prime is 643797839. The reversal of 643797820 is 28797346.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60715 + ... + 70525.

It is an arithmetic number, because the mean of its divisors is an integer number (29980566).

Almost surely, 2^643797820 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643797820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (719533584).

643797820 is an abundant number, since it is smaller than the sum of its proper divisors (795269348).

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

643797820 is a wasteful number, since it uses less digits than its factorization.

643797820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10030 (or 10028 counting only the distinct ones).

The product of its (nonzero) digits is 508032, while the sum is 46.

The square root of 643797820 is about 25373.1712641522. The cubic root of 643797820 is about 863.4751309589.

The spelling of 643797820 in words is "six hundred forty-three million, seven hundred ninety-seven thousand, eight hundred twenty".