3666661 has 2 divisors, whose sum is σ = 3666662. Its totient is φ = 3666660.

The previous prime is 3666659. The next prime is 3666703. The reversal of 3666661 is 1666663.

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., 3629025 + 37636 = 1905^2 + 194^2 .

It is a cyclic number.

It is not a de Polignac number, because 3666661 - 2¹ = 3666659 is a prime.

Together with 3666659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3666461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1833330 + 1833331.

It is an arithmetic number, because the mean of its divisors is an integer number (1833331).

Almost surely, 2^3666661 is an apocalyptic number.

It is an amenable number.

3666661 is a deficient number, since it is larger than the sum of its proper divisors (1).

3666661 is an equidigital number, since it uses as much as digits as its factorization.

3666661 is an odious number, because the sum of its binary digits is odd.

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

The square root of 3666661 is about 1914.8527358520. The cubic root of 3666661 is about 154.2020875352.

The spelling of 3666661 in words is "three million, six hundred sixty-six thousand, six hundred sixty-one".