1366639 has 2 divisors, whose sum is σ = 1366640. Its totient is φ = 1366638.

The previous prime is 1366627. The next prime is 1366643. The reversal of 1366639 is 9366631.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1366639 - 2¹⁹ = 842351 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1366609) 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, 683319 + 683320.

It is an arithmetic number, because the mean of its divisors is an integer number (683320).

2^1366639 is an apocalyptic number.

1366639 is a deficient number, since it is larger than the sum of its proper divisors (1).

1366639 is an equidigital number, since it uses as much as digits as its factorization.

1366639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496, while the sum is 34.

The square root of 1366639 is about 1169.0333613717. The cubic root of 1366639 is about 110.9731558601.

The spelling of 1366639 in words is "one million, three hundred sixty-six thousand, six hundred thirty-nine".