821297261 has 2 divisors, whose sum is σ = 821297262. Its totient is φ = 821297260.

The previous prime is 821297227. The next prime is 821297293. The reversal of 821297261 is 162792128.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 436392100 + 384905161 = 20890^2 + 19619^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-821297261 is a prime.

It is a super-2 number, since 2×821297261² = 1349058381852204242, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821297161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410648630 + 410648631.

It is an arithmetic number, because the mean of its divisors is an integer number (410648631).

Almost surely, 2^821297261 is an apocalyptic number.

It is an amenable number.

821297261 is a deficient number, since it is larger than the sum of its proper divisors (1).

821297261 is an equidigital number, since it uses as much as digits as its factorization.

821297261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 38.

The square root of 821297261 is about 28658.2843345515. The cubic root of 821297261 is about 936.4834890561.

The spelling of 821297261 in words is "eight hundred twenty-one million, two hundred ninety-seven thousand, two hundred sixty-one".