21406384 has 10 divisors (see below), whose sum is σ = 41474900. Its totient is φ = 10703184.

The previous prime is 21406367. The next prime is 21406391. The reversal of 21406384 is 48360412.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 668934 + ... + 668965.

It is an arithmetic number, because the mean of its divisors is an integer number (4147490).

Almost surely, 2^21406384 is an apocalyptic number.

It is an amenable number.

21406384 is a deficient number, since it is larger than the sum of its proper divisors (20068516).

21406384 is a wasteful number, since it uses less digits than its factorization.

21406384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1337907 (or 1337901 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 21406384 is about 4626.7033620063. The cubic root of 21406384 is about 277.6607147386.

Adding to 21406384 its reverse (48360412), we get a palindrome (69766796).

The spelling of 21406384 in words is "twenty-one million, four hundred six thousand, three hundred eighty-four".