21017445 has 16 divisors (see below), whose sum is σ = 33725760. Its totient is φ = 11176704.

The previous prime is 21017419. The next prime is 21017453. The reversal of 21017445 is 54471012.

It is not a de Polignac number, because 21017445 - 2⁷ = 21017317 is a prime.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 3837 + ... + 7533.

It is an arithmetic number, because the mean of its divisors is an integer number (2107860).

Almost surely, 2^21017445 is an apocalyptic number.

It is an amenable number.

21017445 is a deficient number, since it is larger than the sum of its proper divisors (12708315).

21017445 is a wasteful number, since it uses less digits than its factorization.

21017445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4084.

The product of its (nonzero) digits is 1120, while the sum is 24.

The square root of 21017445 is about 4584.4787053710. The cubic root of 21017445 is about 275.9687924177.

Adding to 21017445 its reverse (54471012), we get a palindrome (75488457).

The spelling of 21017445 in words is "twenty-one million, seventeen thousand, four hundred forty-five".