643636620 has 216 divisors, whose sum is σ = 2194828272. Its totient is φ = 151372800.

The previous prime is 643636589. The next prime is 643636673. The reversal of 643636620 is 26636346.

643636620 is a `hidden beast` number, since 643 + 6 + 3 + 6 + 6 + 2 + 0 = 666.

643636620 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 8816904 + ... + 8816976.

It is an arithmetic number, because the mean of its divisors is an integer number (10161242).

Almost surely, 2^643636620 is an apocalyptic number.

643636620 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643636620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1097414136).

643636620 is an abundant number, since it is smaller than the sum of its proper divisors (1551191652).

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

643636620 is a wasteful number, since it uses less digits than its factorization.

643636620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233 (or 155 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 36.

The square root of 643636620 is about 25369.9944816707. The cubic root of 643636620 is about 863.4030566701.

The spelling of 643636620 in words is "six hundred forty-three million, six hundred thirty-six thousand, six hundred twenty".