643816873924 has 81 divisors (see below), whose sum is σ = 1347877084743. Its totient is φ = 268290864576.

The previous prime is 643816873901. The next prime is 643816873937. The reversal of 643816873924 is 429378618346.

The square root of 643816873924 is 802382.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 52812636100 + 591004237824 = 229810^2 + 768768^2 .

It is a super-2 number, since 2×643816873924² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 415633102 + ... + 415634650.

Almost surely, 2^643816873924 is an apocalyptic number.

643816873924 is the 802382-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643816873924

643816873924 is an abundant number, since it is smaller than the sum of its proper divisors (704060210819).

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

643816873924 is an equidigital number, since it uses as much as digits as its factorization.

643816873924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3190 (or 1595 counting only the distinct ones).

The product of its digits is 41803776, while the sum is 61.

The spelling of 643816873924 in words is "six hundred forty-three billion, eight hundred sixteen million, eight hundred seventy-three thousand, nine hundred twenty-four".