6661409 has 2 divisors, whose sum is σ = 6661410. Its totient is φ = 6661408.

The previous prime is 6661379. The next prime is 6661423. The reversal of 6661409 is 9041666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6615184 + 46225 = 2572^2 + 215^2 .

It is a cyclic number.

It is not a de Polignac number, because 6661409 - 2¹⁶ = 6595873 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (6661429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3330704 + 3330705.

It is an arithmetic number, because the mean of its divisors is an integer number (3330705).

Almost surely, 2^6661409 is an apocalyptic number.

It is an amenable number.

6661409 is a deficient number, since it is larger than the sum of its proper divisors (1).

6661409 is an equidigital number, since it uses as much as digits as its factorization.

6661409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 6661409 is about 2580.9705538808. The cubic root of 6661409 is about 188.1577162263.

The spelling of 6661409 in words is "six million, six hundred sixty-one thousand, four hundred nine".