643649760 has 384 divisors, whose sum is σ = 2474962560. Its totient is φ = 155271168.

The previous prime is 643649759. The next prime is 643649761. The reversal of 643649760 is 67946346.

It is an interprime number because it is at equal distance from previous prime (643649759) and next prime (643649761).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643649761) 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 63 ways as a sum of consecutive naturals, for example, 4099602 + ... + 4099758.

It is an arithmetic number, because the mean of its divisors is an integer number (6445215).

Almost surely, 2^643649760 is an apocalyptic number.

643649760 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643649760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1237481280).

643649760 is an abundant number, since it is smaller than the sum of its proper divisors (1831312800).

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

643649760 is a wasteful number, since it uses less digits than its factorization.

643649760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267 (or 253 counting only the distinct ones).

The product of its (nonzero) digits is 653184, while the sum is 45.

The square root of 643649760 is about 25370.2534476895. The cubic root of 643649760 is about 863.4089321587.

The spelling of 643649760 in words is "six hundred forty-three million, six hundred forty-nine thousand, seven hundred sixty".