821261 has 8 divisors (see below), whose sum is σ = 979584. Its totient is φ = 673200.

The previous prime is 821209. The next prime is 821263. The reversal of 821261 is 162128.

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

It is a cyclic number.

It is not a de Polignac number, because 821261 - 2¹⁴ = 804877 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 (821263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2390 + ... + 2711.

It is an arithmetic number, because the mean of its divisors is an integer number (122448).

2⁸²¹²⁶¹ is an apocalyptic number.

It is an amenable number.

821261 is a deficient number, since it is larger than the sum of its proper divisors (158323).

821261 is a wasteful number, since it uses less digits than its factorization.

821261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5131.

The product of its digits is 192, while the sum is 20.

The square root of 821261 is about 906.2345171091. The cubic root of 821261 is about 93.6469706662.

Adding to 821261 its reverse (162128), we get a palindrome (983389).

The spelling of 821261 in words is "eight hundred twenty-one thousand, two hundred sixty-one".