21423404 has 6 divisors (see below), whose sum is σ = 37490964. Its totient is φ = 10711700.

The previous prime is 21423403. The next prime is 21423421. The reversal of 21423404 is 40432412.

It is not an unprimeable number, because it can be changed into a prime (21423403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2677922 + ... + 2677929.

It is an arithmetic number, because the mean of its divisors is an integer number (6248494).

Almost surely, 2^21423404 is an apocalyptic number.

It is an amenable number.

21423404 is a deficient number, since it is larger than the sum of its proper divisors (16067560).

21423404 is a wasteful number, since it uses less digits than its factorization.

21423404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5355855 (or 5355853 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 21423404 is about 4628.5423191325. The cubic root of 21423404 is about 277.7342836553.

Adding to 21423404 its reverse (40432412), we get a palindrome (61855816).

The spelling of 21423404 in words is "twenty-one million, four hundred twenty-three thousand, four hundred four".