221312845 has 16 divisors (see below), whose sum is σ = 287672112. Its totient is φ = 162478080.

The previous prime is 221312843. The next prime is 221312869. The reversal of 221312845 is 548213122.

It can be written as a sum of positive squares in 8 ways, for example, as 19616041 + 201696804 = 4429^2 + 14202^2 .

It is not a de Polignac number, because 221312845 - 2¹ = 221312843 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221312843) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1405 + ... + 21085.

It is an arithmetic number, because the mean of its divisors is an integer number (17979507).

Almost surely, 2^221312845 is an apocalyptic number.

It is an amenable number.

221312845 is a deficient number, since it is larger than the sum of its proper divisors (66359267).

221312845 is a wasteful number, since it uses less digits than its factorization.

221312845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19872.

The product of its digits is 3840, while the sum is 28.

The square root of 221312845 is about 14876.5871422178. The cubic root of 221312845 is about 604.8795106456.

Adding to 221312845 its reverse (548213122), we get a palindrome (769525967).

It can be divided in two parts, 22131 and 2845, that added together give a triangular number (24976 = T₂₂₃).

The spelling of 221312845 in words is "two hundred twenty-one million, three hundred twelve thousand, eight hundred forty-five".