21092505 has 16 divisors (see below), whose sum is σ = 38569344. Its totient is φ = 9642240.

The previous prime is 21092501. The next prime is 21092507. The reversal of 21092505 is 50529012.

It is not a de Polignac number, because 21092505 - 2² = 21092501 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21092501) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 100336 + ... + 100545.

It is an arithmetic number, because the mean of its divisors is an integer number (2410584).

Almost surely, 2^21092505 is an apocalyptic number.

It is an amenable number.

21092505 is a deficient number, since it is larger than the sum of its proper divisors (17476839).

21092505 is a wasteful number, since it uses less digits than its factorization.

21092505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200896.

The product of its (nonzero) digits is 900, while the sum is 24.

The square root of 21092505 is about 4592.6577272860. The cubic root of 21092505 is about 276.2969262979.

The spelling of 21092505 in words is "twenty-one million, ninety-two thousand, five hundred five".