21055289 has 4 divisors (see below), whose sum is σ = 21194880. Its totient is φ = 20915700.

The previous prime is 21055277. The next prime is 21055291. The reversal of 21055289 is 98255012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21055289 - 2⁸ = 21055033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21055259) by changing a digit.

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, 69569 + ... + 69870.

It is an arithmetic number, because the mean of its divisors is an integer number (5298720).

Almost surely, 2^21055289 is an apocalyptic number.

It is an amenable number.

21055289 is a deficient number, since it is larger than the sum of its proper divisors (139591).

21055289 is a wasteful number, since it uses less digits than its factorization.

21055289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139590.

The product of its (nonzero) digits is 7200, while the sum is 32.

The square root of 21055289 is about 4588.6042540189. The cubic root of 21055289 is about 276.1343295211.

The spelling of 21055289 in words is "twenty-one million, fifty-five thousand, two hundred eighty-nine".