21306075 has 24 divisors (see below), whose sum is σ = 40259328. Its totient is φ = 9739680.

The previous prime is 21306023. The next prime is 21306079. The reversal of 21306075 is 57060312.

It is not a de Polignac number, because 21306075 - 2⁹ = 21305563 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21306079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19767 + ... + 20816.

It is an arithmetic number, because the mean of its divisors is an integer number (1677472).

Almost surely, 2^21306075 is an apocalyptic number.

21306075 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21306075 is a deficient number, since it is larger than the sum of its proper divisors (18953253).

21306075 is a wasteful number, since it uses less digits than its factorization.

21306075 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40603 (or 40598 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 24.

The square root of 21306075 is about 4615.8504091879. The cubic root of 21306075 is about 277.2263351895.

Adding to 21306075 its reverse (57060312), we get a palindrome (78366387).

The spelling of 21306075 in words is "twenty-one million, three hundred six thousand, seventy-five".