21236525 has 6 divisors (see below), whose sum is σ = 26333322. Its totient is φ = 16989200.

The previous prime is 21236491. The next prime is 21236561. The reversal of 21236525 is 52563212.

It can be written as a sum of positive squares in 3 ways, for example, as 6135529 + 15100996 = 2477^2 + 3886^2 .

It is not a de Polignac number, because 21236525 - 2¹² = 21232429 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21236494 and 21236503.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 424706 + ... + 424755.

It is an arithmetic number, because the mean of its divisors is an integer number (4388887).

Almost surely, 2^21236525 is an apocalyptic number.

21236525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21236525 is a deficient number, since it is larger than the sum of its proper divisors (5096797).

21236525 is an equidigital number, since it uses as much as digits as its factorization.

21236525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 849471 (or 849466 counting only the distinct ones).

The product of its digits is 3600, while the sum is 26.

The square root of 21236525 is about 4608.3104279117. The cubic root of 21236525 is about 276.9243538739.

Adding to 21236525 its reverse (52563212), we get a palindrome (73799737).

The spelling of 21236525 in words is "twenty-one million, two hundred thirty-six thousand, five hundred twenty-five".