821489971 has 2 divisors, whose sum is σ = 821489972. Its totient is φ = 821489970.

The previous prime is 821489957. The next prime is 821490013. The reversal of 821489971 is 179984128.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 821489971 - 2⁷ = 821489843 is a prime.

It is not a weakly prime, because it can be changed into another prime (821489671) 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, 410744985 + 410744986.

It is an arithmetic number, because the mean of its divisors is an integer number (410744986).

Almost surely, 2^821489971 is an apocalyptic number.

821489971 is a deficient number, since it is larger than the sum of its proper divisors (1).

821489971 is an equidigital number, since it uses as much as digits as its factorization.

821489971 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 290304, while the sum is 49.

The square root of 821489971 is about 28661.6463414089. The cubic root of 821489971 is about 936.5567291314.

The spelling of 821489971 in words is "eight hundred twenty-one million, four hundred eighty-nine thousand, nine hundred seventy-one".