21169855 has 16 divisors (see below), whose sum is σ = 30035520. Its totient is φ = 14015232.

The previous prime is 21169853. The next prime is 21169859. The reversal of 21169855 is 55896112.

It is not a de Polignac number, because 21169855 - 2¹ = 21169853 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21169853) 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 15 ways as a sum of consecutive naturals, for example, 9414 + ... + 11443.

It is an arithmetic number, because the mean of its divisors is an integer number (1877220).

Almost surely, 2^21169855 is an apocalyptic number.

21169855 is a deficient number, since it is larger than the sum of its proper divisors (8865665).

21169855 is a wasteful number, since it uses less digits than its factorization.

21169855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20898.

The product of its digits is 21600, while the sum is 37.

The square root of 21169855 is about 4601.0710709573. The cubic root of 21169855 is about 276.6342577479.

The spelling of 21169855 in words is "twenty-one million, one hundred sixty-nine thousand, eight hundred fifty-five".