87821291 has 4 divisors (see below), whose sum is σ = 91639632. Its totient is φ = 84002952.

The previous prime is 87821243. The next prime is 87821299. The reversal of 87821291 is 19212878.

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

It is a cyclic number.

It is not a de Polignac number, because 87821291 - 2¹⁰ = 87820267 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87821299) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1909136 + ... + 1909181.

It is an arithmetic number, because the mean of its divisors is an integer number (22909908).

Almost surely, 2^87821291 is an apocalyptic number.

87821291 is a deficient number, since it is larger than the sum of its proper divisors (3818341).

87821291 is a wasteful number, since it uses less digits than its factorization.

87821291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3818340.

The product of its digits is 16128, while the sum is 38.

The square root of 87821291 is about 9371.3014571083. The cubic root of 87821291 is about 444.4947191716.

The spelling of 87821291 in words is "eighty-seven million, eight hundred twenty-one thousand, two hundred ninety-one".