6643789 has 2 divisors, whose sum is σ = 6643790. Its totient is φ = 6643788.

The previous prime is 6643781. The next prime is 6643807. The reversal of 6643789 is 9873466.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3553225 + 3090564 = 1885^2 + 1758^2 .

It is a cyclic number.

It is not a de Polignac number, because 6643789 - 2³ = 6643781 is a prime.

It is a d-powerful number, because it can be written as 6⁶ + 6⁸ + 4⁷ + 3 + 7⁶ + 8³ + 9⁷ .

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6643781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3321894 + 3321895.

It is an arithmetic number, because the mean of its divisors is an integer number (3321895).

Almost surely, 2^6643789 is an apocalyptic number.

It is an amenable number.

6643789 is a deficient number, since it is larger than the sum of its proper divisors (1).

6643789 is an equidigital number, since it uses as much as digits as its factorization.

6643789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 43.

The square root of 6643789 is about 2577.5548490769. The cubic root of 6643789 is about 187.9916719564.

The spelling of 6643789 in words is "six million, six hundred forty-three thousand, seven hundred eighty-nine".