1306639 has 4 divisors (see below), whose sum is σ = 1314040. Its totient is φ = 1299240.

The previous prime is 1306633. The next prime is 1306661. The reversal of 1306639 is 9366031.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1306639 - 2¹¹ = 1304591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1306633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3429 + ... + 3790.

It is an arithmetic number, because the mean of its divisors is an integer number (328510).

2^1306639 is an apocalyptic number.

1306639 is a deficient number, since it is larger than the sum of its proper divisors (7401).

1306639 is an equidigital number, since it uses as much as digits as its factorization.

1306639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7400.

The product of its (nonzero) digits is 2916, while the sum is 28.

The square root of 1306639 is about 1143.0831115890. The cubic root of 1306639 is about 109.3247615809.

The spelling of 1306639 in words is "one million, three hundred six thousand, six hundred thirty-nine".