21404455 has 8 divisors (see below), whose sum is σ = 25995312. Its totient is φ = 16916928.

The previous prime is 21404437. The next prime is 21404459. The reversal of 21404455 is 55440412.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21404455 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404459) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25374 + ... + 26203.

It is an arithmetic number, because the mean of its divisors is an integer number (3249414).

Almost surely, 2^21404455 is an apocalyptic number.

21404455 is a deficient number, since it is larger than the sum of its proper divisors (4590857).

21404455 is an equidigital number, since it uses as much as digits as its factorization.

21404455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51665.

The product of its (nonzero) digits is 3200, while the sum is 25.

The square root of 21404455 is about 4626.4948935452. The cubic root of 21404455 is about 277.6523741799.

Adding to 21404455 its reverse (55440412), we get a palindrome (76844867).

The spelling of 21404455 in words is "twenty-one million, four hundred four thousand, four hundred fifty-five".