6628781 has 2 divisors, whose sum is σ = 6628782. Its totient is φ = 6628780.

The previous prime is 6628753. The next prime is 6628813. The reversal of 6628781 is 1878266.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4583881 + 2044900 = 2141^2 + 1430^2 .

It is a cyclic number.

It is not a de Polignac number, because 6628781 - 2⁶ = 6628717 is a prime.

It is a super-2 number, since 2×6628781² = 87881475091922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6628711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3314390 + 3314391.

It is an arithmetic number, because the mean of its divisors is an integer number (3314391).

Almost surely, 2^6628781 is an apocalyptic number.

It is an amenable number.

6628781 is a deficient number, since it is larger than the sum of its proper divisors (1).

6628781 is an equidigital number, since it uses as much as digits as its factorization.

6628781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32256, while the sum is 38.

The square root of 6628781 is about 2574.6419168498. The cubic root of 6628781 is about 187.8500105171.

The spelling of 6628781 in words is "six million, six hundred twenty-eight thousand, seven hundred eighty-one".