1678639 has 2 divisors, whose sum is σ = 1678640. Its totient is φ = 1678638.

The previous prime is 1678627. The next prime is 1678657. The reversal of 1678639 is 9368761.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1678639 - 2¹³ = 1670447 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1678679) 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, 839319 + 839320.

It is an arithmetic number, because the mean of its divisors is an integer number (839320).

2^1678639 is an apocalyptic number.

1678639 is a deficient number, since it is larger than the sum of its proper divisors (1).

1678639 is an equidigital number, since it uses as much as digits as its factorization.

1678639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54432, while the sum is 40.

The square root of 1678639 is about 1295.6230161586. The cubic root of 1678639 is about 118.8463284866.

The spelling of 1678639 in words is "one million, six hundred seventy-eight thousand, six hundred thirty-nine".