21084855 has 24 divisors (see below), whose sum is σ = 37084656. Its totient is φ = 10222080.

The previous prime is 21084853. The next prime is 21084881. The reversal of 21084855 is 55848012.

It is not a de Polignac number, because 21084855 - 2¹ = 21084853 is a prime.

It is a super-2 number, since 2×21084855² = 889142220742050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21084853) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3994 + ... + 7623.

It is an arithmetic number, because the mean of its divisors is an integer number (1545194).

Almost surely, 2^21084855 is an apocalyptic number.

21084855 is a deficient number, since it is larger than the sum of its proper divisors (15999801).

21084855 is a wasteful number, since it uses less digits than its factorization.

21084855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11647 (or 11636 counting only the distinct ones).

The product of its (nonzero) digits is 12800, while the sum is 33.

The square root of 21084855 is about 4591.8248006648. The cubic root of 21084855 is about 276.2635190589.

The spelling of 21084855 in words is "twenty-one million, eighty-four thousand, eight hundred fifty-five".