21110805 has 24 divisors (see below), whose sum is σ = 38519520. Its totient is φ = 10666080.

The previous prime is 21110737. The next prime is 21110813. The reversal of 21110805 is 50801112.

It is not a de Polignac number, because 21110805 - 2¹¹ = 21108757 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 (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11491 + ... + 13200.

It is an arithmetic number, because the mean of its divisors is an integer number (1604980).

Almost surely, 2^21110805 is an apocalyptic number.

It is an amenable number.

21110805 is a deficient number, since it is larger than the sum of its proper divisors (17408715).

21110805 is a wasteful number, since it uses less digits than its factorization.

21110805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24721 (or 24718 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 18.

The square root of 21110805 is about 4594.6496057915. The cubic root of 21110805 is about 276.3768088942.

Adding to 21110805 its reverse (50801112), we get a palindrome (71911917).

The spelling of 21110805 in words is "twenty-one million, one hundred ten thousand, eight hundred five".