811551 has 8 divisors (see below), whose sum is σ = 1165360. Its totient is φ = 499392.

The previous prime is 811523. The next prime is 811553. The reversal of 811551 is 155118.

811551 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 811551 - 2⁵ = 811519 is a prime.

It is a Duffinian number.

811551 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811553) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10366 + ... + 10443.

It is an arithmetic number, because the mean of its divisors is an integer number (145670).

2⁸¹¹⁵⁵¹ is an apocalyptic number.

811551 is a deficient number, since it is larger than the sum of its proper divisors (353809).

811551 is a wasteful number, since it uses less digits than its factorization.

811551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20825.

The product of its digits is 200, while the sum is 21.

The square root of 811551 is about 900.8612545781. The cubic root of 811551 is about 93.2764349916.

Adding to 811551 its reverse (155118), we get a palindrome (966669).

The spelling of 811551 in words is "eight hundred eleven thousand, five hundred fifty-one".