21424406 has 16 divisors (see below), whose sum is σ = 33777744. Its totient is φ = 10178784.

The previous prime is 21424397. The next prime is 21424409. The reversal of 21424406 is 60442412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424409) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 185 + ... + 6548.

It is an arithmetic number, because the mean of its divisors is an integer number (2111109).

Almost surely, 2^21424406 is an apocalyptic number.

21424406 is a deficient number, since it is larger than the sum of its proper divisors (12353338).

21424406 is a wasteful number, since it uses less digits than its factorization.

21424406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6815.

The product of its (nonzero) digits is 1536, while the sum is 23.

The square root of 21424406 is about 4628.6505592883. The cubic root of 21424406 is about 277.7386135836.

Adding to 21424406 its reverse (60442412), we get a palindrome (81866818).

The spelling of 21424406 in words is "twenty-one million, four hundred twenty-four thousand, four hundred six".