87171921 has 12 divisors (see below), whose sum is σ = 126061572. Its totient is φ = 58046976.

The previous prime is 87171893. The next prime is 87171947. The reversal of 87171921 is 12917178.

It can be written as a sum of positive squares in 2 ways, for example, as 4161600 + 83010321 = 2040^2 + 9111^2 .

It is not a de Polignac number, because 87171921 - 2⁶ = 87171857 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (87171961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3265 + ... + 13601.

It is an arithmetic number, because the mean of its divisors is an integer number (10505131).

Almost surely, 2^87171921 is an apocalyptic number.

It is an amenable number.

87171921 is a deficient number, since it is larger than the sum of its proper divisors (38889651).

87171921 is a wasteful number, since it uses less digits than its factorization.

87171921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11280 (or 11277 counting only the distinct ones).

The product of its digits is 7056, while the sum is 36.

The square root of 87171921 is about 9336.5904376276. The cubic root of 87171921 is about 443.3964437388.

The spelling of 87171921 in words is "eighty-seven million, one hundred seventy-one thousand, nine hundred twenty-one".