21440345 has 8 divisors (see below), whose sum is σ = 25755840. Its totient is φ = 17134000.

The previous prime is 21440317. The next prime is 21440351. The reversal of 21440345 is 54304412.

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

It is a de Polignac number, because none of the positive numbers 2^k-21440345 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21440345.

It is an unprimeable number.

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, 4970 + ... + 8220.

It is an arithmetic number, because the mean of its divisors is an integer number (3219480).

Almost surely, 2^21440345 is an apocalyptic number.

It is an amenable number.

21440345 is a deficient number, since it is larger than the sum of its proper divisors (4315495).

21440345 is a wasteful number, since it uses less digits than its factorization.

21440345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4575.

The product of its (nonzero) digits is 1920, while the sum is 23.

The square root of 21440345 is about 4630.3720152921. The cubic root of 21440345 is about 277.8074724107.

Adding to 21440345 its reverse (54304412), we get a palindrome (75744757).

The spelling of 21440345 in words is "twenty-one million, four hundred forty thousand, three hundred forty-five".