87921 has 6 divisors (see below), whose sum is σ = 127010. Its totient is φ = 58608.

The previous prime is 87917. The next prime is 87931. The reversal of 87921 is 12978.

It can be written as a sum of positive squares in only one way, i.e., 69696 + 18225 = 264^2 + 135^2 .

It is not a de Polignac number, because 87921 - 2² = 87917 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 87921.

It is not an unprimeable number, because it can be changed into a prime (87911) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4876 + ... + 4893.

2⁸⁷⁹²¹ is an apocalyptic number.

It is an amenable number.

87921 is a deficient number, since it is larger than the sum of its proper divisors (39089).

87921 is a wasteful number, since it uses less digits than its factorization.

87921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9775 (or 9772 counting only the distinct ones).

The product of its digits is 1008, while the sum is 27.

The square root of 87921 is about 296.5147551135. The cubic root of 87921 is about 44.4662876426.

It can be divided in two parts, 879 and 21, that added together give a square (900 = 30²).

The spelling of 87921 in words is "eighty-seven thousand, nine hundred twenty-one".