821281 has 2 divisors, whose sum is σ = 821282. Its totient is φ = 821280.

The previous prime is 821263. The next prime is 821291. The reversal of 821281 is 182128.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 555025 + 266256 = 745^2 + 516^2 .

It is a cyclic number.

It is not a de Polignac number, because 821281 - 2⁷ = 821153 is a prime.

It is a super-2 number, since 2×821281² = 1349004961922, which contains 22 as substring.

It is a nialpdrome in base 16.

It is not a weakly prime, because it can be changed into another prime (821291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410640 + 410641.

It is an arithmetic number, because the mean of its divisors is an integer number (410641).

2⁸²¹²⁸¹ is an apocalyptic number.

It is an amenable number.

821281 is a deficient number, since it is larger than the sum of its proper divisors (1).

821281 is an equidigital number, since it uses as much as digits as its factorization.

821281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 256, while the sum is 22.

The square root of 821281 is about 906.2455517132. The cubic root of 821281 is about 93.6477308485.

The spelling of 821281 in words is "eight hundred twenty-one thousand, two hundred eighty-one".