812581 has 16 divisors (see below), whose sum is σ = 1035648. Its totient is φ = 619200.

The previous prime is 812527. The next prime is 812587. The reversal of 812581 is 185218.

It is a cyclic number.

It is not a de Polignac number, because 812581 - 2¹¹ = 810533 is a prime.

It is a super-2 number, since 2×812581² = 1320575763122, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

812581 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (812587) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4611 + ... + 4783.

It is an arithmetic number, because the mean of its divisors is an integer number (64728).

2⁸¹²⁵⁸¹ is an apocalyptic number.

It is an amenable number.

812581 is a deficient number, since it is larger than the sum of its proper divisors (223067).

812581 is a wasteful number, since it uses less digits than its factorization.

812581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252.

The product of its digits is 640, while the sum is 25.

The square root of 812581 is about 901.4327484621. The cubic root of 812581 is about 93.3158796728.

Adding to 812581 its reverse (185218), we get a palindrome (997799).

It can be divided in two parts, 81 and 2581, that added together give a palindrome (2662).

The spelling of 812581 in words is "eight hundred twelve thousand, five hundred eighty-one".