21245505 has 16 divisors (see below), whose sum is σ = 34085760. Its totient is φ = 11299968.

The previous prime is 21245489. The next prime is 21245513. The reversal of 21245505 is 50554212.

It is a happy number.

It is not a de Polignac number, because 21245505 - 2⁴ = 21245489 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4404 + ... + 7866.

It is an arithmetic number, because the mean of its divisors is an integer number (2130360).

Almost surely, 2^21245505 is an apocalyptic number.

It is an amenable number.

21245505 is a deficient number, since it is larger than the sum of its proper divisors (12840255).

21245505 is a wasteful number, since it uses less digits than its factorization.

21245505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3880.

The product of its (nonzero) digits is 2000, while the sum is 24.

The square root of 21245505 is about 4609.2846516569. The cubic root of 21245505 is about 276.9633814496.

Adding to 21245505 its reverse (50554212), we get a palindrome (71799717).

The spelling of 21245505 in words is "twenty-one million, two hundred forty-five thousand, five hundred five".