821315281 has 2 divisors, whose sum is σ = 821315282. Its totient is φ = 821315280.

The previous prime is 821315221. The next prime is 821315309. The reversal of 821315281 is 182513128.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 580569025 + 240746256 = 24095^2 + 15516^2 .

It is a cyclic number.

It is not a de Polignac number, because 821315281 - 2⁷ = 821315153 is a prime.

It is a super-2 number, since 2×821315281² = 1349117581608217922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (821315221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410657640 + 410657641.

It is an arithmetic number, because the mean of its divisors is an integer number (410657641).

Almost surely, 2^821315281 is an apocalyptic number.

It is an amenable number.

821315281 is a deficient number, since it is larger than the sum of its proper divisors (1).

821315281 is an equidigital number, since it uses as much as digits as its factorization.

821315281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3840, while the sum is 31.

The square root of 821315281 is about 28658.5987270836. The cubic root of 821315281 is about 936.4903381024.

The spelling of 821315281 in words is "eight hundred twenty-one million, three hundred fifteen thousand, two hundred eighty-one".