1686491 has 2 divisors, whose sum is σ = 1686492. Its totient is φ = 1686490.

The previous prime is 1686479. The next prime is 1686511. The reversal of 1686491 is 1946861.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1686491 - 2¹⁸ = 1424347 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1680491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 843245 + 843246.

It is an arithmetic number, because the mean of its divisors is an integer number (843246).

2^1686491 is an apocalyptic number.

1686491 is a deficient number, since it is larger than the sum of its proper divisors (1).

1686491 is an equidigital number, since it uses as much as digits as its factorization.

1686491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 35.

The square root of 1686491 is about 1298.6496833250. The cubic root of 1686491 is about 119.0313454606.

The spelling of 1686491 in words is "one million, six hundred eighty-six thousand, four hundred ninety-one".