21405376 has 28 divisors (see below), whose sum is σ = 43850560. Its totient is φ = 10356480.

The previous prime is 21405367. The next prime is 21405383. The reversal of 21405376 is 67350412.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 3411 + ... + 7378.

Almost surely, 2^21405376 is an apocalyptic number.

It is an amenable number.

21405376 is an abundant number, since it is smaller than the sum of its proper divisors (22445184).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21405376 is a wasteful number, since it uses less digits than its factorization.

21405376 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10832 (or 10822 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21405376 is about 4626.5944278702. The cubic root of 21405376 is about 277.6563564376.

Adding to 21405376 its reverse (67350412), we get a palindrome (88755788).

The spelling of 21405376 in words is "twenty-one million, four hundred five thousand, three hundred seventy-six".