643434918 has 16 divisors (see below), whose sum is σ = 1470708480. Its totient is φ = 183838536.

The previous prime is 643434889. The next prime is 643434931. The reversal of 643434918 is 819434346.

It is a Harshad number since it is a multiple of its sum of digits (42), and also a Moran number because the ratio is a prime number: 15319879 = 643434918 / (6 + 4 + 3 + 4 + 3 + 4 + 9 + 1 + 8).

It is a self number, because there is not a number n which added to its sum of digits gives 643434918.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7659898 + ... + 7659981.

It is an arithmetic number, because the mean of its divisors is an integer number (91919280).

Almost surely, 2^643434918 is an apocalyptic number.

643434918 is an abundant number, since it is smaller than the sum of its proper divisors (827273562).

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

643434918 is a wasteful number, since it uses less digits than its factorization.

643434918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15319891.

The product of its digits is 248832, while the sum is 42.

The square root of 643434918 is about 25366.0189623835. The cubic root of 643434918 is about 863.3128565412.

The spelling of 643434918 in words is "six hundred forty-three million, four hundred thirty-four thousand, nine hundred eighteen".