643553020 has 72 divisors (see below), whose sum is σ = 1572972912. Its totient is φ = 220239360.

The previous prime is 643553011. The next prime is 643553059. The reversal of 643553020 is 20355346.

It is a super-2 number, since 2×643553020² = 828320979102240800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 643553020.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33319 + ... + 48961.

It is an arithmetic number, because the mean of its divisors is an integer number (21846846).

Almost surely, 2^643553020 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 643553020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (786486456).

643553020 is an abundant number, since it is smaller than the sum of its proper divisors (929419892).

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

643553020 is a wasteful number, since it uses less digits than its factorization.

643553020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15691 (or 15678 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 28.

The square root of 643553020 is about 25368.3468125142. The cubic root of 643553020 is about 863.3656734538.

The spelling of 643553020 in words is "six hundred forty-three million, five hundred fifty-three thousand, twenty".