643828780 has 48 divisors (see below), whose sum is σ = 1546687296. Its totient is φ = 220527360.

The previous prime is 643828741. The next prime is 643828807. The reversal of 643828780 is 87828346.

It is a Smith number, since the sum of its digits (46) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 643828780.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 225522 + ... + 228358.

It is an arithmetic number, because the mean of its divisors is an integer number (32222652).

Almost surely, 2^643828780 is an apocalyptic number.

It is an amenable number.

643828780 is an abundant number, since it is smaller than the sum of its proper divisors (902858516).

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

643828780 is a wasteful number, since it uses less digits than its factorization.

643828780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4474 (or 4472 counting only the distinct ones).

The product of its (nonzero) digits is 516096, while the sum is 46.

The square root of 643828780 is about 25373.7813500471. The cubic root of 643828780 is about 863.4889721374.

The spelling of 643828780 in words is "six hundred forty-three million, eight hundred twenty-eight thousand, seven hundred eighty".