643689552906 has 96 divisors (see below), whose sum is σ = 1457740297728. Its totient is φ = 205048920960.

The previous prime is 643689552893. The next prime is 643689552907. The reversal of 643689552906 is 609255986346.

643689552906 is a `hidden beast` number, since 6 + 43 + 68 + 9 + 5 + 529 + 0 + 6 = 666.

643689552906 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (643689552907) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 14257240 + ... + 14302316.

It is an arithmetic number, because the mean of its divisors is an integer number (15184794768).

Almost surely, 2^643689552906 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643689552906, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (728870148864).

643689552906 is an abundant number, since it is smaller than the sum of its proper divisors (814050744822).

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

643689552906 is a wasteful number, since it uses less digits than its factorization.

643689552906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45436 (or 45433 counting only the distinct ones).

The product of its (nonzero) digits is 83980800, while the sum is 63.

The spelling of 643689552906 in words is "six hundred forty-three billion, six hundred eighty-nine million, five hundred fifty-two thousand, nine hundred six".