87132721 has 4 divisors (see below), whose sum is σ = 93835252. Its totient is φ = 80430192.

The previous prime is 87132719. The next prime is 87132811. The reversal of 87132721 is 12723178.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 21344400 + 65788321 = 4620^2 + 8111^2 .

It is a cyclic number.

It is not a de Polignac number, because 87132721 - 2¹ = 87132719 is a prime.

It is a super-2 number, since 2×87132721² = 15184222137727682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87130721) 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 3 ways as a sum of consecutive naturals, for example, 3351246 + ... + 3351271.

It is an arithmetic number, because the mean of its divisors is an integer number (23458813).

Almost surely, 2^87132721 is an apocalyptic number.

It is an amenable number.

87132721 is a deficient number, since it is larger than the sum of its proper divisors (6702531).

87132721 is a wasteful number, since it uses less digits than its factorization.

87132721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6702530.

The product of its digits is 4704, while the sum is 31.

The square root of 87132721 is about 9334.4909341645. The cubic root of 87132721 is about 443.3299707033.

Adding to 87132721 its reverse (12723178), we get a palindrome (99855899).

The spelling of 87132721 in words is "eighty-seven million, one hundred thirty-two thousand, seven hundred twenty-one".