643400040 has 128 divisors (see below), whose sum is σ = 2097561600. Its totient is φ = 157282560.

The previous prime is 643399963. The next prime is 643400101. The reversal of 643400040 is 40004346.

643400040 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×643400040² = 827927222944003200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 66129 + ... + 75231.

It is an arithmetic number, because the mean of its divisors is an integer number (16387200).

Almost surely, 2^643400040 is an apocalyptic number.

643400040 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 643400040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1048780800).

643400040 is an abundant number, since it is smaller than the sum of its proper divisors (1454161560).

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

643400040 is a wasteful number, since it uses less digits than its factorization.

643400040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9167 (or 9163 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 21.

The square root of 643400040 is about 25365.3314585085. The cubic root of 643400040 is about 863.2972573620.

Adding to 643400040 its reverse (40004346), we get a palindrome (683404386).

The spelling of 643400040 in words is "six hundred forty-three million, four hundred thousand, forty".