1665647 has 2 divisors, whose sum is σ = 1665648. Its totient is φ = 1665646.

The previous prime is 1665623. The next prime is 1665649. The reversal of 1665647 is 7465661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1665647 - 2⁶ = 1665583 is a prime.

Together with 1665649, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1665649) 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 as a sum of consecutive naturals, namely, 832823 + 832824.

It is an arithmetic number, because the mean of its divisors is an integer number (832824).

2^1665647 is an apocalyptic number.

1665647 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665647 is an equidigital number, since it uses as much as digits as its factorization.

1665647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 35.

The square root of 1665647 is about 1290.5994731132. The cubic root of 1665647 is about 118.5389262468.

The spelling of 1665647 in words is "one million, six hundred sixty-five thousand, six hundred forty-seven".