643400540 has 12 divisors (see below), whose sum is σ = 1351141176. Its totient is φ = 257360208.

The previous prime is 643400539. The next prime is 643400557. The reversal of 643400540 is 45004346.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16084994 + ... + 16085033.

It is an arithmetic number, because the mean of its divisors is an integer number (112595098).

Almost surely, 2^643400540 is an apocalyptic number.

It is an amenable number.

643400540 is an abundant number, since it is smaller than the sum of its proper divisors (707740636).

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

643400540 is a wasteful number, since it uses less digits than its factorization.

643400540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32170036 (or 32170034 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 26.

The square root of 643400540 is about 25365.3413144787. The cubic root of 643400540 is about 863.2974809909.

Adding to 643400540 its reverse (45004346), we get a palindrome (688404886).

The spelling of 643400540 in words is "six hundred forty-three million, four hundred thousand, five hundred forty".