871815481721 has 2 divisors, whose sum is σ = 871815481722. Its totient is φ = 871815481720.

The previous prime is 871815481709. The next prime is 871815481729. The reversal of 871815481721 is 127184518178.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 802835712121 + 68979769600 = 896011^2 + 262640^2 .

It is a cyclic number.

It is not a de Polignac number, because 871815481721 - 2⁶ = 871815481657 is a prime.

It is not a weakly prime, because it can be changed into another prime (871815481729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 435907740860 + 435907740861.

It is an arithmetic number, because the mean of its divisors is an integer number (435907740861).

Almost surely, 2^871815481721 is an apocalyptic number.

It is an amenable number.

871815481721 is a deficient number, since it is larger than the sum of its proper divisors (1).

871815481721 is an equidigital number, since it uses as much as digits as its factorization.

871815481721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1003520, while the sum is 53.

Adding to 871815481721 its reverse (127184518178), we get a palindrome (998999999899).

The spelling of 871815481721 in words is "eight hundred seventy-one billion, eight hundred fifteen million, four hundred eighty-one thousand, seven hundred twenty-one".