21616845 has 16 divisors (see below), whose sum is σ = 35240832. Its totient is φ = 11311040.

The previous prime is 21616841. The next prime is 21616853. The reversal of 21616845 is 54861612.

It is not a de Polignac number, because 21616845 - 2² = 21616841 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21616841) 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 15 ways as a sum of consecutive naturals, for example, 12801 + ... + 14390.

It is an arithmetic number, because the mean of its divisors is an integer number (2202552).

Almost surely, 2^21616845 is an apocalyptic number.

It is an amenable number.

21616845 is a deficient number, since it is larger than the sum of its proper divisors (13623987).

21616845 is a wasteful number, since it uses less digits than its factorization.

21616845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27252.

The product of its digits is 11520, while the sum is 33.

The square root of 21616845 is about 4649.3918957214. The cubic root of 21616845 is about 278.5677070978.

The spelling of 21616845 in words is "twenty-one million, six hundred sixteen thousand, eight hundred forty-five".