643937280 has 352 divisors, whose sum is σ = 2419455744. Its totient is φ = 143130624.

The previous prime is 643937251. The next prime is 643937291. The reversal of 643937280 is 82739346.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5698504 + ... + 5698616.

Almost surely, 2^643937280 is an apocalyptic number.

643937280 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 643937280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1209727872).

643937280 is an abundant number, since it is smaller than the sum of its proper divisors (1775518464).

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

643937280 is a wasteful number, since it uses less digits than its factorization.

643937280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 201 (or 183 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 42.

The square root of 643937280 is about 25375.9192936926. The cubic root of 643937280 is about 863.5374753492.

The spelling of 643937280 in words is "six hundred forty-three million, nine hundred thirty-seven thousand, two hundred eighty".