21245515 has 8 divisors (see below), whose sum is σ = 26836560. Its totient is φ = 16101792.

The previous prime is 21245513. The next prime is 21245519. The reversal of 21245515 is 51554212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21245515 - 2¹ = 21245513 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21245515.

It is not an unprimeable number, because it can be changed into a prime (21245513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 111724 + ... + 111913.

It is an arithmetic number, because the mean of its divisors is an integer number (3354570).

Almost surely, 2^21245515 is an apocalyptic number.

21245515 is a deficient number, since it is larger than the sum of its proper divisors (5591045).

21245515 is a wasteful number, since it uses less digits than its factorization.

21245515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223661.

The product of its digits is 2000, while the sum is 25.

The square root of 21245515 is about 4609.2857364238. The cubic root of 21245515 is about 276.9634249041.

Adding to 21245515 its reverse (51554212), we get a palindrome (72799727).

The spelling of 21245515 in words is "twenty-one million, two hundred forty-five thousand, five hundred fifteen".