1666541 has 2 divisors, whose sum is σ = 1666542. Its totient is φ = 1666540.

The previous prime is 1666531. The next prime is 1666559. The reversal of 1666541 is 1456661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1042441 + 624100 = 1021^2 + 790^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666541 - 2⁶ = 1666477 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833270 + 833271.

It is an arithmetic number, because the mean of its divisors is an integer number (833271).

2^1666541 is an apocalyptic number.

It is an amenable number.

1666541 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666541 is an equidigital number, since it uses as much as digits as its factorization.

1666541 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 29.

The square root of 1666541 is about 1290.9457773276. The cubic root of 1666541 is about 118.5601301886.

The spelling of 1666541 in words is "one million, six hundred sixty-six thousand, five hundred forty-one".