1285639 has 4 divisors (see below), whose sum is σ = 1320424. Its totient is φ = 1250856.

The previous prime is 1285633. The next prime is 1285649. The reversal of 1285639 is 9365821.

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 1285639 - 2⁵ = 1285607 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 (1285633) 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, 17337 + ... + 17410.

It is an arithmetic number, because the mean of its divisors is an integer number (330106).

2^1285639 is an apocalyptic number.

1285639 is a deficient number, since it is larger than the sum of its proper divisors (34785).

1285639 is an equidigital number, since it uses as much as digits as its factorization.

1285639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34784.

The product of its digits is 12960, while the sum is 34.

The square root of 1285639 is about 1133.8602206621. The cubic root of 1285639 is about 108.7359148535.

The spelling of 1285639 in words is "one million, two hundred eighty-five thousand, six hundred thirty-nine".