6661663 has 6 divisors (see below), whose sum is σ = 6749864. Its totient is φ = 6574596.

The previous prime is 6661661. The next prime is 6661687. The reversal of 6661663 is 3661666.

It is a happy number.

It is not a de Polignac number, because 6661663 - 2¹ = 6661661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6661661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6406 + ... + 7372.

Almost surely, 2^6661663 is an apocalyptic number.

6661663 is a deficient number, since it is larger than the sum of its proper divisors (88201).

6661663 is an frugal number, since it uses more digits than its factorization.

6661663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1133 (or 1050 counting only the distinct ones).

The product of its digits is 23328, while the sum is 34.

The square root of 6661663 is about 2581.0197597074. The cubic root of 6661663 is about 188.1601076850.

The spelling of 6661663 in words is "six million, six hundred sixty-one thousand, six hundred sixty-three".