21122505 has 32 divisors (see below), whose sum is σ = 38361600. Its totient is φ = 11022336.

The previous prime is 21122473. The next prime is 21122561. The reversal of 21122505 is 50522112.

It is not a de Polignac number, because 21122505 - 2⁵ = 21122473 is a prime.

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 31 ways as a sum of consecutive naturals, for example, 4681 + ... + 8009.

It is an arithmetic number, because the mean of its divisors is an integer number (1198800).

Almost surely, 2^21122505 is an apocalyptic number.

It is an amenable number.

21122505 is a deficient number, since it is larger than the sum of its proper divisors (17239095).

21122505 is a wasteful number, since it uses less digits than its factorization.

21122505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3390 (or 3384 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21122505 is about 4595.9226494796. The cubic root of 21122505 is about 276.4278571839.

Adding to 21122505 its reverse (50522112), we get a palindrome (71644617).

The spelling of 21122505 in words is "twenty-one million, one hundred twenty-two thousand, five hundred five".