87781221 has 24 divisors (see below), whose sum is σ = 139707360. Its totient is φ = 52668000.

The previous prime is 87781201. The next prime is 87781237. The reversal of 87781221 is 12218778.

It is a happy number.

It is not a de Polignac number, because 87781221 - 2⁶ = 87781157 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87781201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5610 + ... + 14388.

It is an arithmetic number, because the mean of its divisors is an integer number (5821140).

Almost surely, 2^87781221 is an apocalyptic number.

It is an amenable number.

87781221 is a deficient number, since it is larger than the sum of its proper divisors (51926139).

87781221 is a wasteful number, since it uses less digits than its factorization.

87781221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8897 (or 8894 counting only the distinct ones).

The product of its digits is 12544, while the sum is 36.

The square root of 87781221 is about 9369.1633030917. The cubic root of 87781221 is about 444.4271060574.

Adding to 87781221 its reverse (12218778), we get a palindrome (99999999).

It can be divided in two parts, 8778 and 1221, that added together give a palindrome (9999).

The spelling of 87781221 in words is "eighty-seven million, seven hundred eighty-one thousand, two hundred twenty-one".