21145115 has 4 divisors (see below), whose sum is σ = 25374144. Its totient is φ = 16916088.

The previous prime is 21145109. The next prime is 21145141. The reversal of 21145115 is 51154112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21145115 - 2⁶ = 21145051 is a prime.

It is a super-3 number, since 3×21145115³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2114507 + ... + 2114516.

It is an arithmetic number, because the mean of its divisors is an integer number (6343536).

Almost surely, 2^21145115 is an apocalyptic number.

21145115 is a deficient number, since it is larger than the sum of its proper divisors (4229029).

21145115 is an equidigital number, since it uses as much as digits as its factorization.

21145115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4229028.

The product of its digits is 200, while the sum is 20.

The square root of 21145115 is about 4598.3817805833. The cubic root of 21145115 is about 276.5264535249.

Adding to 21145115 its reverse (51154112), we get a palindrome (72299227).

The spelling of 21145115 in words is "twenty-one million, one hundred forty-five thousand, one hundred fifteen".