871816721 has 2 divisors, whose sum is σ = 871816722. Its totient is φ = 871816720.

The previous prime is 871816669. The next prime is 871816793. The reversal of 871816721 is 127618178.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 688485121 + 183331600 = 26239^2 + 13540^2 .

It is a cyclic number.

It is not a de Polignac number, because 871816721 - 2⁶ = 871816657 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (871816021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 435908360 + 435908361.

It is an arithmetic number, because the mean of its divisors is an integer number (435908361).

Almost surely, 2^871816721 is an apocalyptic number.

It is an amenable number.

871816721 is a deficient number, since it is larger than the sum of its proper divisors (1).

871816721 is an equidigital number, since it uses as much as digits as its factorization.

871816721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 37632, while the sum is 41.

The square root of 871816721 is about 29526.5426523323. The cubic root of 871816721 is about 955.3042974632.

The spelling of 871816721 in words is "eight hundred seventy-one million, eight hundred sixteen thousand, seven hundred twenty-one".