21252505 has 16 divisors (see below), whose sum is σ = 26657280. Its totient is φ = 16244928.

The previous prime is 21252503. The next prime is 21252509. The reversal of 21252505 is 50525212.

It is a cyclic number.

It is not a de Polignac number, because 21252505 - 2¹ = 21252503 is a prime.

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

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (21252503) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14224 + ... + 15646.

It is an arithmetic number, because the mean of its divisors is an integer number (1666080).

Almost surely, 2^21252505 is an apocalyptic number.

It is an amenable number.

21252505 is a deficient number, since it is larger than the sum of its proper divisors (5404775).

21252505 is a wasteful number, since it uses less digits than its factorization.

21252505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1560.

The product of its (nonzero) digits is 1000, while the sum is 22.

The square root of 21252505 is about 4610.0439260380. The cubic root of 21252505 is about 276.9937962092.

Adding to 21252505 its reverse (50525212), we get a palindrome (71777717).

The spelling of 21252505 in words is "twenty-one million, two hundred fifty-two thousand, five hundred five".