21424417 has 12 divisors (see below), whose sum is σ = 25783380. Its totient is φ = 17729376.

The previous prime is 21424409. The next prime is 21424421. The reversal of 21424417 is 71442412.

It can be written as a sum of positive squares in 2 ways, for example, as 4769856 + 16654561 = 2184^2 + 4081^2 .

It is not a de Polignac number, because 21424417 - 2³ = 21424409 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21424391 and 21424400.

It is not an unprimeable number, because it can be changed into a prime (21424217) 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 11 ways as a sum of consecutive naturals, for example, 6118 + ... + 8959.

It is an arithmetic number, because the mean of its divisors is an integer number (2148615).

Almost surely, 2^21424417 is an apocalyptic number.

It is an amenable number.

21424417 is a deficient number, since it is larger than the sum of its proper divisors (4358963).

21424417 is a wasteful number, since it uses less digits than its factorization.

21424417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15120 (or 15113 counting only the distinct ones).

The product of its digits is 1792, while the sum is 25.

The square root of 21424417 is about 4628.6517475394. The cubic root of 21424417 is about 277.7386611170.

Adding to 21424417 its reverse (71442412), we get a palindrome (92866829).

The spelling of 21424417 in words is "twenty-one million, four hundred twenty-four thousand, four hundred seventeen".