21530025 has 36 divisors (see below), whose sum is σ = 42073200. Its totient is φ = 10437600.

The previous prime is 21530017. The next prime is 21530077. The reversal of 21530025 is 52003512.

It is a happy number.

It is not a de Polignac number, because 21530025 - 2³ = 21530017 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1875 + ... + 6824.

It is an arithmetic number, because the mean of its divisors is an integer number (1168700).

Almost surely, 2^21530025 is an apocalyptic number.

21530025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21530025 is a deficient number, since it is larger than the sum of its proper divisors (20543175).

21530025 is a wasteful number, since it uses less digits than its factorization.

21530025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8726 (or 8718 counting only the distinct ones).

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

The square root of 21530025 is about 4640.0457971878. The cubic root of 21530025 is about 278.1942684011.

Adding to 21530025 its reverse (52003512), we get a palindrome (73533537).

The spelling of 21530025 in words is "twenty-one million, five hundred thirty thousand, twenty-five".