643091072 has 64 divisors (see below), whose sum is σ = 1388758560. Its totient is φ = 294865920.

The previous prime is 643091069. The next prime is 643091077. The reversal of 643091072 is 270190346.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×643091072² = 827132253772218368, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is not an unprimeable number, because it can be changed into a prime (643091077) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 270047 + ... + 272417.

Almost surely, 2^643091072 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 643091072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (694379280).

643091072 is an abundant number, since it is smaller than the sum of its proper divisors (745667488).

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

643091072 is a wasteful number, since it uses less digits than its factorization.

643091072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2561 (or 2549 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 32.

The square root of 643091072 is about 25359.2403671719. The cubic root of 643091072 is about 863.1590468565.

The spelling of 643091072 in words is "six hundred forty-three million, ninety-one thousand, seventy-two".