643126660 has 96 divisors (see below), whose sum is σ = 1586148480. Its totient is φ = 216422400.

The previous prime is 643126657. The next prime is 643126663. The reversal of 643126660 is 66621346.

It is an interprime number because it is at equal distance from previous prime (643126657) and next prime (643126663).

It is a super-2 number, since 2×643126660² = 827223801605511200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is not an unprimeable number, because it can be changed into a prime (643126663) 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 31 ways as a sum of consecutive naturals, for example, 226731 + ... + 229549.

It is an arithmetic number, because the mean of its divisors is an integer number (16522380).

Almost surely, 2^643126660 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643126660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (793074240).

643126660 is an abundant number, since it is smaller than the sum of its proper divisors (943021820).

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

643126660 is a wasteful number, since it uses less digits than its factorization.

643126660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2917 (or 2915 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 34.

The square root of 643126660 is about 25359.9420346341. The cubic root of 643126660 is about 863.1749686748.

The spelling of 643126660 in words is "six hundred forty-three million, one hundred twenty-six thousand, six hundred sixty".