21344215 has 4 divisors (see below), whose sum is σ = 25613064. Its totient is φ = 17075368.

The previous prime is 21344209. The next prime is 21344237. The reversal of 21344215 is 51244312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21344215 - 2¹⁵ = 21311447 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2134417 + ... + 2134426.

It is an arithmetic number, because the mean of its divisors is an integer number (6403266).

Almost surely, 2^21344215 is an apocalyptic number.

21344215 is a deficient number, since it is larger than the sum of its proper divisors (4268849).

21344215 is an equidigital number, since it uses as much as digits as its factorization.

21344215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4268848.

The product of its digits is 960, while the sum is 22.

The square root of 21344215 is about 4619.9799783116. The cubic root of 21344215 is about 277.3916575140.

Adding to 21344215 its reverse (51244312), we get a palindrome (72588527).

The spelling of 21344215 in words is "twenty-one million, three hundred forty-four thousand, two hundred fifteen".