21221125 has 8 divisors (see below), whose sum is σ = 26484120. Its totient is φ = 16976800.

The previous prime is 21221113. The next prime is 21221129. The reversal of 21221125 is 52112212.

It is a happy number.

21221125 is nontrivially palindromic in base 4.

It can be written as a sum of positive squares in 4 ways, for example, as 591361 + 20629764 = 769^2 + 4542^2 .

It is not a de Polignac number, because 21221125 - 2⁹ = 21220613 is a prime.

It is a super-3 number, since 3×21221125³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 21221099 and 21221108.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221129) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 84760 + ... + 85009.

It is an arithmetic number, because the mean of its divisors is an integer number (3310515).

Almost surely, 2^21221125 is an apocalyptic number.

21221125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21221125 is a deficient number, since it is larger than the sum of its proper divisors (5262995).

21221125 is an equidigital number, since it uses as much as digits as its factorization.

21221125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169784 (or 169774 counting only the distinct ones).

The product of its digits is 80, while the sum is 16.

The square root of 21221125 is about 4606.6392305020. The cubic root of 21221125 is about 276.8573990038.

Adding to 21221125 its reverse (52112212), we get a palindrome (73333337).

The spelling of 21221125 in words is "twenty-one million, two hundred twenty-one thousand, one hundred twenty-five".