21224865 has 32 divisors (see below), whose sum is σ = 35239680. Its totient is φ = 10900224.

The previous prime is 21224849. The next prime is 21224867. The reversal of 21224865 is 56842212.

It is not a de Polignac number, because 21224865 - 2⁴ = 21224849 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21224867) 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 31 ways as a sum of consecutive naturals, for example, 92571 + ... + 92799.

It is an arithmetic number, because the mean of its divisors is an integer number (1101240).

Almost surely, 2^21224865 is an apocalyptic number.

It is an amenable number.

21224865 is a deficient number, since it is larger than the sum of its proper divisors (14014815).

21224865 is a wasteful number, since it uses less digits than its factorization.

21224865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 441.

The product of its digits is 7680, while the sum is 30.

The square root of 21224865 is about 4607.0451484656. The cubic root of 21224865 is about 276.8736624496.

The spelling of 21224865 in words is "twenty-one million, two hundred twenty-four thousand, eight hundred sixty-five".