643987242 has 72 divisors (see below), whose sum is σ = 1468527840. Its totient is φ = 203893200.

The previous prime is 643987231. The next prime is 643987243. The reversal of 643987242 is 242789346.

643987242 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (643987243) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1020267 + ... + 1020897.

It is an arithmetic number, because the mean of its divisors is an integer number (20396220).

Almost surely, 2^643987242 is an apocalyptic number.

643987242 is a gapful number since it is divisible by the number (62) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 643987242, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (734263920).

643987242 is an abundant number, since it is smaller than the sum of its proper divisors (824540598).

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

643987242 is a wasteful number, since it uses less digits than its factorization.

643987242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 760 (or 726 counting only the distinct ones).

The product of its digits is 580608, while the sum is 45.

The square root of 643987242 is about 25376.9037118400. The cubic root of 643987242 is about 863.5598082404.

The spelling of 643987242 in words is "six hundred forty-three million, nine hundred eighty-seven thousand, two hundred forty-two".