21043121225 has 48 divisors (see below), whose sum is σ = 30175711488. Its totient is φ = 14258979840.

The previous prime is 21043121221. The next prime is 21043121287. The reversal of 21043121225 is 52212134012.

It is not a de Polignac number, because 21043121225 - 2² = 21043121221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21043121225.

It is not an unprimeable number, because it can be changed into a prime (21043121221) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5584292 + ... + 5588058.

It is an arithmetic number, because the mean of its divisors is an integer number (628660656).

Almost surely, 2^21043121225 is an apocalyptic number.

21043121225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21043121225 is a deficient number, since it is larger than the sum of its proper divisors (9132590263).

21043121225 is a wasteful number, since it uses less digits than its factorization.

21043121225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4154 (or 4149 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

Adding to 21043121225 its reverse (52212134012), we get a palindrome (73255255237).

The spelling of 21043121225 in words is "twenty-one billion, forty-three million, one hundred twenty-one thousand, two hundred twenty-five".