821617393 has 2 divisors, whose sum is σ = 821617394. Its totient is φ = 821617392.

The previous prime is 821617373. The next prime is 821617411. The reversal of 821617393 is 393716128.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 714867169 + 106750224 = 26737^2 + 10332^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-821617393 is a prime.

It is not a weakly prime, because it can be changed into another prime (821617343) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410808696 + 410808697.

It is an arithmetic number, because the mean of its divisors is an integer number (410808697).

Almost surely, 2^821617393 is an apocalyptic number.

It is an amenable number.

821617393 is a deficient number, since it is larger than the sum of its proper divisors (1).

821617393 is an equidigital number, since it uses as much as digits as its factorization.

821617393 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 40.

The square root of 821617393 is about 28663.8691212474. The cubic root of 821617393 is about 936.6051499952.

The spelling of 821617393 in words is "eight hundred twenty-one million, six hundred seventeen thousand, three hundred ninety-three".