21344409 has 12 divisors (see below), whose sum is σ = 30933396. Its totient is φ = 14182272.

The previous prime is 21344369. The next prime is 21344417. The reversal of 21344409 is 90444312.

21344409 is a `hidden beast` number, since 213 + 4 + 440 + 9 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 138384 + 21206025 = 372^2 + 4605^2 .

It is not a de Polignac number, because 21344409 - 2¹² = 21340313 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21344419) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 972 + ... + 6605.

It is an arithmetic number, because the mean of its divisors is an integer number (2577783).

Almost surely, 2^21344409 is an apocalyptic number.

It is an amenable number.

21344409 is a deficient number, since it is larger than the sum of its proper divisors (9588987).

21344409 is a wasteful number, since it uses less digits than its factorization.

21344409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7896 (or 7893 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 21344409 is about 4620.0009740259. Note that the first 3 decimals coincide. The cubic root of 21344409 is about 277.3924979262.

The spelling of 21344409 in words is "twenty-one million, three hundred forty-four thousand, four hundred nine".