21155128 has 16 divisors (see below), whose sum is σ = 39743280. Its totient is φ = 10556928.

The previous prime is 21155119. The next prime is 21155131. The reversal of 21155128 is 82155112.

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 3 ways as a sum of consecutive naturals, for example, 2325 + ... + 6907.

It is an arithmetic number, because the mean of its divisors is an integer number (2483955).

Almost surely, 2^21155128 is an apocalyptic number.

It is an amenable number.

21155128 is a deficient number, since it is larger than the sum of its proper divisors (18588152).

21155128 is a wasteful number, since it uses less digits than its factorization.

21155128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5166 (or 5162 counting only the distinct ones).

The product of its digits is 800, while the sum is 25.

The square root of 21155128 is about 4599.4704042966. The cubic root of 21155128 is about 276.5700951642.

The spelling of 21155128 in words is "twenty-one million, one hundred fifty-five thousand, one hundred twenty-eight".