21404345 has 8 divisors (see below), whose sum is σ = 25843776. Its totient is φ = 17017776.

The previous prime is 21404321. The next prime is 21404359. The reversal of 21404345 is 54340412.

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

It is a cyclic number.

It is not a de Polignac number, because 21404345 - 2¹⁸ = 21142201 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21404345.

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, 12317 + ... + 13946.

It is an arithmetic number, because the mean of its divisors is an integer number (3230472).

Almost surely, 2^21404345 is an apocalyptic number.

It is an amenable number.

21404345 is a deficient number, since it is larger than the sum of its proper divisors (4439431).

21404345 is a wasteful number, since it uses less digits than its factorization.

21404345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26431.

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

The square root of 21404345 is about 4626.4830054805. The cubic root of 21404345 is about 277.6518985497.

Adding to 21404345 its reverse (54340412), we get a palindrome (75744757).

The spelling of 21404345 in words is "twenty-one million, four hundred four thousand, three hundred forty-five".