21424207 has 4 divisors (see below), whose sum is σ = 24484816. Its totient is φ = 18363600.

The previous prime is 21424189. The next prime is 21424213. The reversal of 21424207 is 70242412.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21424207 - 2⁷ = 21424079 is a prime.

It is a Duffinian number.

It is a congruent number.

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 (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1530294 + ... + 1530307.

It is an arithmetic number, because the mean of its divisors is an integer number (6121204).

Almost surely, 2^21424207 is an apocalyptic number.

21424207 is a deficient number, since it is larger than the sum of its proper divisors (3060609).

21424207 is an equidigital number, since it uses as much as digits as its factorization.

21424207 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3060608.

The product of its (nonzero) digits is 896, while the sum is 22.

The square root of 21424207 is about 4628.6290626923. The cubic root of 21424207 is about 277.7377536585.

Adding to 21424207 its reverse (70242412), we get a palindrome (91666619).

The spelling of 21424207 in words is "twenty-one million, four hundred twenty-four thousand, two hundred seven".