221121225 has 96 divisors (see below), whose sum is σ = 443304960. Its totient is φ = 107412480.

The previous prime is 221121223. The next prime is 221121253. The reversal of 221121225 is 522121122.

It is not a de Polignac number, because 221121225 - 2¹ = 221121223 is a prime.

It is a super-2 number, since 2×221121225² = 97789192291001250, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 221121198 and 221121207.

It is not an unprimeable number, because it can be changed into a prime (221121223) 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 95 ways as a sum of consecutive naturals, for example, 991464 + ... + 991686.

It is an arithmetic number, because the mean of its divisors is an integer number (4617760).

Almost surely, 2^221121225 is an apocalyptic number.

221121225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

221121225 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

221121225 is a wasteful number, since it uses less digits than its factorization.

221121225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 368 (or 357 counting only the distinct ones).

The product of its digits is 160, while the sum is 18.

The square root of 221121225 is about 14870.1454263232. The cubic root of 221121225 is about 604.7048853243.

Adding to 221121225 its reverse (522121122), we get a palindrome (743242347).

It can be divided in two parts, 2211 and 21225, that added together give a triangular number (23436 = T₂₁₆).

The spelling of 221121225 in words is "two hundred twenty-one million, one hundred twenty-one thousand, two hundred twenty-five".