21854865 has 16 divisors (see below), whose sum is σ = 35462016. Its totient is φ = 11491200.

The previous prime is 21854837. The next prime is 21854867. The reversal of 21854865 is 56845812.

It is not a de Polignac number, because 21854865 - 2⁶ = 21854801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21854867) 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, 9196 + ... + 11325.

It is an arithmetic number, because the mean of its divisors is an integer number (2216376).

Almost surely, 2^21854865 is an apocalyptic number.

It is an amenable number.

21854865 is a deficient number, since it is larger than the sum of its proper divisors (13607151).

21854865 is a wasteful number, since it uses less digits than its factorization.

21854865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20600.

The product of its digits is 76800, while the sum is 39.

The square root of 21854865 is about 4674.9187158709. The cubic root of 21854865 is about 279.5864004102.

The spelling of 21854865 in words is "twenty-one million, eight hundred fifty-four thousand, eight hundred sixty-five".