21044205125 has 8 divisors (see below), whose sum is σ = 26263168152. Its totient is φ = 16835364000.

The previous prime is 21044205121. The next prime is 21044205151. The reversal of 21044205125 is 52150244012.

It can be written as a sum of positive squares in 4 ways, for example, as 2874782689 + 18169422436 = 53617^2 + 134794^2 .

It is not a de Polignac number, because 21044205125 - 2² = 21044205121 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21044205094 and 21044205103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21044205121) 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, 84176696 + ... + 84176945.

It is an arithmetic number, because the mean of its divisors is an integer number (3282896019).

Almost surely, 2^21044205125 is an apocalyptic number.

21044205125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21044205125 is a deficient number, since it is larger than the sum of its proper divisors (5218963027).

21044205125 is an equidigital number, since it uses as much as digits as its factorization.

21044205125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168353656 (or 168353646 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 26.

Adding to 21044205125 its reverse (52150244012), we get a palindrome (73194449137).

The spelling of 21044205125 in words is "twenty-one billion, forty-four million, two hundred five thousand, one hundred twenty-five".