21126025 has 6 divisors (see below), whose sum is σ = 26196302. Its totient is φ = 16900800.

The previous prime is 21126023. The next prime is 21126031. The reversal of 21126025 is 52062112.

It can be written as a sum of positive squares in 3 ways, for example, as 2809 + 21123216 = 53^2 + 4596^2 .

It is not a de Polignac number, because 21126025 - 2¹ = 21126023 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21125993 and 21126011.

It is not an unprimeable number, because it can be changed into a prime (21126023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 422496 + ... + 422545.

Almost surely, 2^21126025 is an apocalyptic number.

21126025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21126025 is a deficient number, since it is larger than the sum of its proper divisors (5070277).

21126025 is an equidigital number, since it uses as much as digits as its factorization.

21126025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 845051 (or 845046 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21126025 is about 4596.3055816601. The cubic root of 21126025 is about 276.4432116130.

Adding to 21126025 its reverse (52062112), we get a palindrome (73188137).

The spelling of 21126025 in words is "twenty-one million, one hundred twenty-six thousand, twenty-five".