643738000 has 80 divisors (see below), whose sum is σ = 1586188656. Its totient is φ = 252595200.

The previous prime is 643737989. The next prime is 643738003. The reversal of 643738000 is 837346.

It can be written as a sum of positive squares in 8 ways, for example, as 40347904 + 603390096 = 6352^2 + 24564^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×643738000² = 828797225288000000, which contains 22 as substring.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (643738003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 102964 + ... + 109036.

Almost surely, 2^643738000 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 643738000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (793094328).

643738000 is an abundant number, since it is smaller than the sum of its proper divisors (942450656).

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

643738000 is a wasteful number, since it uses less digits than its factorization.

643738000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6149 (or 6133 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 31.

The square root of 643738000 is about 25371.9924326017. The cubic root of 643738000 is about 863.4483861846.

The spelling of 643738000 in words is "six hundred forty-three million, seven hundred thirty-eight thousand".