21445065 has 24 divisors (see below), whose sum is σ = 38455560. Its totient is φ = 11042304.

The previous prime is 21445037. The next prime is 21445111. The reversal of 21445065 is 56054412.

It can be written as a sum of positive squares in 4 ways, for example, as 8311689 + 13133376 = 2883^2 + 3624^2 .

It is not a de Polignac number, because 21445065 - 2⁵ = 21445033 is a prime.

It is a Curzon number.

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 6912 + ... + 9521.

It is an arithmetic number, because the mean of its divisors is an integer number (1602315).

Almost surely, 2^21445065 is an apocalyptic number.

It is an amenable number.

21445065 is a deficient number, since it is larger than the sum of its proper divisors (17010495).

21445065 is a wasteful number, since it uses less digits than its factorization.

21445065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16473 (or 16470 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The square root of 21445065 is about 4630.8816655147. The cubic root of 21445065 is about 277.8278569561.

Adding to 21445065 its reverse (56054412), we get a palindrome (77499477).

The spelling of 21445065 in words is "twenty-one million, four hundred forty-five thousand, sixty-five".