21308145 has 16 divisors (see below), whose sum is σ = 34672320. Its totient is φ = 11171264.

The previous prime is 21308141. The next prime is 21308149. The reversal of 21308145 is 54180312.

It is an interprime number because it is at equal distance from previous prime (21308141) and next prime (21308149).

It is a cyclic number.

It is not a de Polignac number, because 21308145 - 2² = 21308141 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21308141) 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 15 ways as a sum of consecutive naturals, for example, 11154 + ... + 12923.

It is an arithmetic number, because the mean of its divisors is an integer number (2167020).

Almost surely, 2^21308145 is an apocalyptic number.

It is an amenable number.

21308145 is a deficient number, since it is larger than the sum of its proper divisors (13364175).

21308145 is a wasteful number, since it uses less digits than its factorization.

21308145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24144.

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 21308145 is about 4616.0746311125. The cubic root of 21308145 is about 277.2353129095.

Adding to 21308145 its reverse (54180312), we get a palindrome (75488457).

The spelling of 21308145 in words is "twenty-one million, three hundred eight thousand, one hundred forty-five".