21101845 has 8 divisors (see below), whose sum is σ = 26811864. Its totient is φ = 15888384.

The previous prime is 21101819. The next prime is 21101849. The reversal of 21101845 is 54810112.

It can be written as a sum of positive squares in 4 ways, for example, as 3411409 + 17690436 = 1847^2 + 4206^2 .

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 21101845 - 2⁵ = 21101813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101849) 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 7 ways as a sum of consecutive naturals, for example, 124044 + ... + 124213.

It is an arithmetic number, because the mean of its divisors is an integer number (3351483).

Almost surely, 2^21101845 is an apocalyptic number.

It is an amenable number.

21101845 is a deficient number, since it is larger than the sum of its proper divisors (5710019).

21101845 is a wasteful number, since it uses less digits than its factorization.

21101845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248279.

The product of its (nonzero) digits is 320, while the sum is 22.

The square root of 21101845 is about 4593.6744551611. The cubic root of 21101845 is about 276.3377027487.

Adding to 21101845 its reverse (54810112), we get a palindrome (75911957).

The spelling of 21101845 in words is "twenty-one million, one hundred one thousand, eight hundred forty-five".