21424402 has 16 divisors (see below), whose sum is σ = 32892480. Its totient is φ = 10462192.

The previous prime is 21424397. The next prime is 21424409. The reversal of 21424402 is 20442412.

It is a self number, because there is not a number n which added to its sum of digits gives 21424402.

It is not an unprimeable number, because it can be changed into a prime (21424409) 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 7 ways as a sum of consecutive naturals, for example, 37773 + ... + 38335.

It is an arithmetic number, because the mean of its divisors is an integer number (2055780).

Almost surely, 2^21424402 is an apocalyptic number.

21424402 is a deficient number, since it is larger than the sum of its proper divisors (11468078).

21424402 is a wasteful number, since it uses less digits than its factorization.

21424402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 977.

The product of its (nonzero) digits is 512, while the sum is 19.

The square root of 21424402 is about 4628.6501271969. The cubic root of 21424402 is about 277.7385962988.

Adding to 21424402 its reverse (20442412), we get a palindrome (41866814).

The spelling of 21424402 in words is "twenty-one million, four hundred twenty-four thousand, four hundred two".