221685516873 has 10 divisors (see below), whose sum is σ = 331159846314. Its totient is φ = 147790344528.

The previous prime is 221685516869. The next prime is 221685516881. The reversal of 221685516873 is 378615586122.

221685516873 is a `hidden beast` number, since 2 + 2 + 1 + 6 + 8 + 551 + 6 + 87 + 3 = 666.

It can be written as a sum of positive squares in only one way, i.e., 193505851449 + 28179665424 = 439893^2 + 167868^2 .

It is not a de Polignac number, because 221685516873 - 2² = 221685516869 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221685516673) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1368429036 + ... + 1368429197.

Almost surely, 2^221685516873 is an apocalyptic number.

It is an amenable number.

221685516873 is a deficient number, since it is larger than the sum of its proper divisors (109474329441).

221685516873 is an equidigital number, since it uses as much as digits as its factorization.

221685516873 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2736858245 (or 2736858236 counting only the distinct ones).

The product of its digits is 4838400, while the sum is 54.

The spelling of 221685516873 in words is "two hundred twenty-one billion, six hundred eighty-five million, five hundred sixteen thousand, eight hundred seventy-three".