1328581 has 4 divisors (see below), whose sum is σ = 1344672. Its totient is φ = 1312492.

The previous prime is 1328573. The next prime is 1328603. The reversal of 1328581 is 1858231.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1858231 = 89 ⋅20879.

It is a cyclic number.

It is not a de Polignac number, because 1328581 - 2³ = 1328573 is a prime.

It is a super-2 number, since 2×1328581² = 3530254947122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1328501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7921 + ... + 8086.

It is an arithmetic number, because the mean of its divisors is an integer number (336168).

2^1328581 is an apocalyptic number.

It is an amenable number.

1328581 is a deficient number, since it is larger than the sum of its proper divisors (16091).

1328581 is an equidigital number, since it uses as much as digits as its factorization.

1328581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16090.

The product of its digits is 1920, while the sum is 28.

The square root of 1328581 is about 1152.6408807604. The cubic root of 1328581 is about 109.9333204701.

It can be divided in two parts, 13285 and 81, that added together give a triangular number (13366 = T₁₆₃).

The spelling of 1328581 in words is "one million, three hundred twenty-eight thousand, five hundred eighty-one".