6643780 has 96 divisors (see below), whose sum is σ = 17273088. Its totient is φ = 2112000.

The previous prime is 6643739. The next prime is 6643781. The reversal of 6643780 is 873466.

It is not an unprimeable number, because it can be changed into a prime (6643781) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 65730 + ... + 65830.

It is an arithmetic number, because the mean of its divisors is an integer number (179928).

Almost surely, 2^6643780 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 6643780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8636544).

6643780 is an abundant number, since it is smaller than the sum of its proper divisors (10629308).

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

6643780 is a wasteful number, since it uses less digits than its factorization.

6643780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157 (or 155 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 34.

The square root of 6643780 is about 2577.5531032357. The cubic root of 6643780 is about 187.9915870688.

It can be divided in two parts, 664 and 3780, that multiplied together give a triangular number (2509920 = T₂₂₄₀).

The spelling of 6643780 in words is "six million, six hundred forty-three thousand, seven hundred eighty".