87821131 has 4 divisors (see below), whose sum is σ = 87973912. Its totient is φ = 87668352.

The previous prime is 87821101. The next prime is 87821137. The reversal of 87821131 is 13112878.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13112878 = 2 ⋅6556439.

It is a cyclic number.

It is not a de Polignac number, because 87821131 - 2⁷ = 87821003 is a prime.

It is a super-2 number, since 2×87821131² = 15425102100238322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 87821093 and 87821102.

It is not an unprimeable number, because it can be changed into a prime (87821137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75525 + ... + 76678.

It is an arithmetic number, because the mean of its divisors is an integer number (21993478).

Almost surely, 2^87821131 is an apocalyptic number.

87821131 is a deficient number, since it is larger than the sum of its proper divisors (152781).

87821131 is a wasteful number, since it uses less digits than its factorization.

87821131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152780.

The product of its digits is 2688, while the sum is 31.

The square root of 87821131 is about 9371.2929204032. The cubic root of 87821131 is about 444.4944492325.

The spelling of 87821131 in words is "eighty-seven million, eight hundred twenty-one thousand, one hundred thirty-one".