21530855 has 16 divisors (see below), whose sum is σ = 26723424. Its totient is φ = 16640640.

The previous prime is 21530849. The next prime is 21530867. The reversal of 21530855 is 55803512.

It is not a de Polignac number, because 21530855 - 2¹² = 21526759 is a prime.

It is a Duffinian number.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 33164 + ... + 33806.

It is an arithmetic number, because the mean of its divisors is an integer number (1670214).

Almost surely, 2^21530855 is an apocalyptic number.

21530855 is a deficient number, since it is larger than the sum of its proper divisors (5192569).

21530855 is a wasteful number, since it uses less digits than its factorization.

21530855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 866.

The product of its (nonzero) digits is 6000, while the sum is 29.

The square root of 21530855 is about 4640.1352350982. The cubic root of 21530855 is about 278.1978432270.

The spelling of 21530855 in words is "twenty-one million, five hundred thirty thousand, eight hundred fifty-five".