21115055 has 8 divisors (see below), whose sum is σ = 27287232. Its totient is φ = 15592608.

The previous prime is 21115027. The next prime is 21115063. The reversal of 21115055 is 55051112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21115055 - 2⁶ = 21114991 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 7 ways as a sum of consecutive naturals, for example, 162359 + ... + 162488.

It is an arithmetic number, because the mean of its divisors is an integer number (3410904).

Almost surely, 2^21115055 is an apocalyptic number.

21115055 is a deficient number, since it is larger than the sum of its proper divisors (6172177).

21115055 is a wasteful number, since it uses less digits than its factorization.

21115055 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324865.

The product of its (nonzero) digits is 250, while the sum is 20.

The square root of 21115055 is about 4595.1120769792. The cubic root of 21115055 is about 276.3953542571.

Adding to 21115055 its reverse (55051112), we get a palindrome (76166167).

The spelling of 21115055 in words is "twenty-one million, one hundred fifteen thousand, fifty-five".