821857913 has 2 divisors, whose sum is σ = 821857914. Its totient is φ = 821857912.

The previous prime is 821857903. The next prime is 821857943. The reversal of 821857913 is 319758128.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 670395664 + 151462249 = 25892^2 + 12307^2 .

It is a cyclic number.

It is not a de Polignac number, because 821857913 - 2¹⁴ = 821841529 is a prime.

It is not a weakly prime, because it can be changed into another prime (821857903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410928956 + 410928957.

It is an arithmetic number, because the mean of its divisors is an integer number (410928957).

Almost surely, 2^821857913 is an apocalyptic number.

It is an amenable number.

821857913 is a deficient number, since it is larger than the sum of its proper divisors (1).

821857913 is an equidigital number, since it uses as much as digits as its factorization.

821857913 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120960, while the sum is 44.

The square root of 821857913 is about 28668.0643399585. The cubic root of 821857913 is about 936.6965349042.

The spelling of 821857913 in words is "eight hundred twenty-one million, eight hundred fifty-seven thousand, nine hundred thirteen".