21011445 has 72 divisors (see below), whose sum is σ = 45687096. Its totient is φ = 8854272.

The previous prime is 21011423. The next prime is 21011447. The reversal of 21011445 is 54411012.

21011445 is a `hidden beast` number, since 210 + 11 + 445 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 3896676 + 17114769 = 1974^2 + 4137^2 .

It is not a de Polignac number, because 21011445 - 2⁵ = 21011413 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011447) by changing a digit.

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 71 ways as a sum of consecutive naturals, for example, 28299 + ... + 29031.

It is an arithmetic number, because the mean of its divisors is an integer number (634543).

Almost surely, 2^21011445 is an apocalyptic number.

It is an amenable number.

21011445 is an abundant number, since it is smaller than the sum of its proper divisors (24675651).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21011445 is a wasteful number, since it uses less digits than its factorization.

21011445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 771 (or 761 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 21011445 is about 4583.8242767366. The cubic root of 21011445 is about 275.9425289915.

Adding to 21011445 its reverse (54411012), we get a palindrome (75422457).

The spelling of 21011445 in words is "twenty-one million, eleven thousand, four hundred forty-five".