21003525 has 36 divisors (see below), whose sum is σ = 37867492. Its totient is φ = 11128320.

The previous prime is 21003509. The next prime is 21003527. The reversal of 21003525 is 52530012.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 3814209 + 17189316 = 1953^2 + 4146^2 .

It is not a de Polignac number, because 21003525 - 2⁴ = 21003509 is a prime.

It is a super-2 number, since 2×21003525² = 882296124851250, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21003498 and 21003507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003527) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 62157 + ... + 62493.

Almost surely, 2^21003525 is an apocalyptic number.

21003525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21003525 is a deficient number, since it is larger than the sum of its proper divisors (16863967).

21003525 is a wasteful number, since it uses less digits than its factorization.

21003525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 630 (or 622 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 21003525 is about 4582.9602878489. The cubic root of 21003525 is about 275.9078536121.

Adding to 21003525 its reverse (52530012), we get a palindrome (73533537).

It can be divided in two parts, 21003 and 525, that added together give a triangular number (21528 = T₂₀₇).

The spelling of 21003525 in words is "twenty-one million, three thousand, five hundred twenty-five".