87173158921 has 2 divisors, whose sum is σ = 87173158922. Its totient is φ = 87173158920.

The previous prime is 87173158907. The next prime is 87173158957. The reversal of 87173158921 is 12985137178.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74166896896 + 13006262025 = 272336^2 + 114045^2 .

It is a cyclic number.

It is not a de Polignac number, because 87173158921 - 2⁹ = 87173158409 is a prime.

It is not a weakly prime, because it can be changed into another prime (87173158991) 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, 43586579460 + 43586579461.

It is an arithmetic number, because the mean of its divisors is an integer number (43586579461).

Almost surely, 2^87173158921 is an apocalyptic number.

It is an amenable number.

87173158921 is a deficient number, since it is larger than the sum of its proper divisors (1).

87173158921 is an equidigital number, since it uses as much as digits as its factorization.

87173158921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 846720, while the sum is 52.

The spelling of 87173158921 in words is "eighty-seven billion, one hundred seventy-three million, one hundred fifty-eight thousand, nine hundred twenty-one".