21424165 has 16 divisors (see below), whose sum is σ = 31110912. Its totient is φ = 13826304.

The previous prime is 21424159. The next prime is 21424171. The reversal of 21424165 is 56142412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21424159) and next prime (21424171).

It is not a de Polignac number, because 21424165 - 2¹¹ = 21422117 is a prime.

It is a congruent number.

It is an unprimeable number.

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, 17409 + ... + 18598.

It is an arithmetic number, because the mean of its divisors is an integer number (1944432).

Almost surely, 2^21424165 is an apocalyptic number.

It is an amenable number.

21424165 is a deficient number, since it is larger than the sum of its proper divisors (9686747).

21424165 is a wasteful number, since it uses less digits than its factorization.

21424165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36036.

The product of its digits is 1920, while the sum is 25.

The square root of 21424165 is about 4628.6245257096. The cubic root of 21424165 is about 277.7375721661.

Adding to 21424165 its reverse (56142412), we get a palindrome (77566577).

The spelling of 21424165 in words is "twenty-one million, four hundred twenty-four thousand, one hundred sixty-five".