643988380 has 36 divisors (see below), whose sum is σ = 1573174008. Its totient is φ = 220795680.

The previous prime is 643988377. The next prime is 643988383. The reversal of 643988380 is 83889346.

It is an interprime number because it is at equal distance from previous prime (643988377) and next prime (643988383).

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643988383) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 327586 + ... + 329545.

It is an arithmetic number, because the mean of its divisors is an integer number (43699278).

Almost surely, 2^643988380 is an apocalyptic number.

It is an amenable number.

643988380 is an abundant number, since it is smaller than the sum of its proper divisors (929185628).

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

643988380 is a wasteful number, since it uses less digits than its factorization.

643988380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 657154 (or 657145 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 49.

The square root of 643988380 is about 25376.9261337933. The cubic root of 643988380 is about 863.5603169101.

The spelling of 643988380 in words is "six hundred forty-three million, nine hundred eighty-eight thousand, three hundred eighty".