21424565 has 16 divisors (see below), whose sum is σ = 26688000. Its totient is φ = 16493760.

The previous prime is 21424549. The next prime is 21424577. The reversal of 21424565 is 56542412.

It is not a de Polignac number, because 21424565 - 2⁴ = 21424549 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42686 + ... + 43184.

It is an arithmetic number, because the mean of its divisors is an integer number (1668000).

Almost surely, 2^21424565 is an apocalyptic number.

It is an amenable number.

21424565 is a deficient number, since it is larger than the sum of its proper divisors (5263435).

21424565 is a wasteful number, since it uses less digits than its factorization.

21424565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 812.

The product of its digits is 9600, while the sum is 29.

The square root of 21424565 is about 4628.6677348887. The cubic root of 21424565 is about 277.7393006557.

Adding to 21424565 its reverse (56542412), we get a palindrome (77966977).

The spelling of 21424565 in words is "twenty-one million, four hundred twenty-four thousand, five hundred sixty-five".