1581005 has 4 divisors (see below), whose sum is σ = 1897212. Its totient is φ = 1264800.

The previous prime is 1580987. The next prime is 1581007. The reversal of 1581005 is 5001851.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5001851 = 1069 ⋅4679.

It can be written as a sum of positive squares in 2 ways, for example, as 1142761 + 438244 = 1069^2 + 662^2 .

It is not a de Polignac number, because 1581005 - 2¹⁶ = 1515469 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1581007) 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, 158096 + ... + 158105.

It is an arithmetic number, because the mean of its divisors is an integer number (474303).

2^1581005 is an apocalyptic number.

It is an amenable number.

1581005 is a deficient number, since it is larger than the sum of its proper divisors (316207).

1581005 is an equidigital number, since it uses as much as digits as its factorization.

1581005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316206.

The product of its (nonzero) digits is 200, while the sum is 20.

The square root of 1581005 is about 1257.3802129825. The cubic root of 1581005 is about 116.4960180874.

Adding to 1581005 its reverse (5001851), we get a palindrome (6582856).

The spelling of 1581005 in words is "one million, five hundred eighty-one thousand, five".