643122018 has 240 divisors, whose sum is σ = 1869362880. Its totient is φ = 161663040.

The previous prime is 643122017. The next prime is 643122037. The reversal of 643122018 is 810221346.

643122018 is a `hidden beast` number, since 6 + 431 + 220 + 1 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 643121982 and 643122000.

It is not an unprimeable number, because it can be changed into a prime (643122017) by changing a digit.

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 119 ways as a sum of consecutive naturals, for example, 5900148 + ... + 5900256.

It is an arithmetic number, because the mean of its divisors is an integer number (7789012).

Almost surely, 2^643122018 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643122018, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (934681440).

643122018 is an abundant number, since it is smaller than the sum of its proper divisors (1226240862).

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

643122018 is a wasteful number, since it uses less digits than its factorization.

643122018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195 (or 175 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 643122018 is about 25359.8505121777. The cubic root of 643122018 is about 863.1728919103.

The spelling of 643122018 in words is "six hundred forty-three million, one hundred twenty-two thousand, eighteen".