21216454 has 8 divisors (see below), whose sum is σ = 36371088. Its totient is φ = 9092760.

The previous prime is 21216451. The next prime is 21216457. The reversal of 21216454 is 45461212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21216451) and next prime (21216457).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21216451) 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 3 ways as a sum of consecutive naturals, for example, 757717 + ... + 757744.

It is an arithmetic number, because the mean of its divisors is an integer number (4546386).

Almost surely, 2^21216454 is an apocalyptic number.

21216454 is a deficient number, since it is larger than the sum of its proper divisors (15154634).

21216454 is a wasteful number, since it uses less digits than its factorization.

21216454 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1515470.

The product of its digits is 1920, while the sum is 25.

The square root of 21216454 is about 4606.1322169473. The cubic root of 21216454 is about 276.8370844068.

Adding to 21216454 its reverse (45461212), we get a palindrome (66677666).

The spelling of 21216454 in words is "twenty-one million, two hundred sixteen thousand, four hundred fifty-four".