811621 has 4 divisors (see below), whose sum is σ = 817600. Its totient is φ = 805644.

The previous prime is 811619. The next prime is 811627. The reversal of 811621 is 126118.

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: 126118 = 2 ⋅63059.

It is not a de Polignac number, because 811621 - 2¹ = 811619 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 (811627) 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, 2781 + ... + 3058.

It is an arithmetic number, because the mean of its divisors is an integer number (204400).

2⁸¹¹⁶²¹ is an apocalyptic number.

It is an amenable number.

811621 is a deficient number, since it is larger than the sum of its proper divisors (5979).

811621 is a wasteful number, since it uses less digits than its factorization.

811621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5978.

The product of its digits is 96, while the sum is 19.

The square root of 811621 is about 900.9001054501. The cubic root of 811621 is about 93.2791167548.

Adding to 811621 its reverse (126118), we get a palindrome (937739).

The spelling of 811621 in words is "eight hundred eleven thousand, six hundred twenty-one".