641638000 has 160 divisors (see below), whose sum is σ = 1634181120. Its totient is φ = 243360000.

The previous prime is 641637989. The next prime is 641638001. The reversal of 641638000 is 836146.

It is a self number, because there is not a number n which added to its sum of digits gives 641638000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641638001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4897935 + ... + 4898065.

It is an arithmetic number, because the mean of its divisors is an integer number (10213632).

Almost surely, 2^641638000 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 641638000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (817090560).

641638000 is an abundant number, since it is smaller than the sum of its proper divisors (992543120).

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

641638000 is a wasteful number, since it uses less digits than its factorization.

641638000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264 (or 248 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 641638000 is about 25330.5744111735. The cubic root of 641638000 is about 862.5084505228.

The spelling of 641638000 in words is "six hundred forty-one million, six hundred thirty-eight thousand".