21130555 has 16 divisors (see below), whose sum is σ = 26127360. Its totient is φ = 16398688.

The previous prime is 21130511. The next prime is 21130573. The reversal of 21130555 is 55503112.

It is a cyclic number.

It is not a de Polignac number, because 21130555 - 2¹¹ = 21128507 is a prime.

It is an unprimeable number.

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, 24054 + ... + 24916.

It is an arithmetic number, because the mean of its divisors is an integer number (1632960).

Almost surely, 2^21130555 is an apocalyptic number.

21130555 is a deficient number, since it is larger than the sum of its proper divisors (4996805).

21130555 is an equidigital number, since it uses as much as digits as its factorization.

21130555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1010.

The product of its (nonzero) digits is 750, while the sum is 22.

The square root of 21130555 is about 4596.7983423248. The cubic root of 21130555 is about 276.4629692066.

Adding to 21130555 its reverse (55503112), we get a palindrome (76633667).

The spelling of 21130555 in words is "twenty-one million, one hundred thirty thousand, five hundred fifty-five".