21550289 has 2 divisors, whose sum is σ = 21550290. Its totient is φ = 21550288.

The previous prime is 21550283. The next prime is 21550327. The reversal of 21550289 is 98205512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20566225 + 984064 = 4535^2 + 992^2 .

It is a cyclic number.

It is not a de Polignac number, because 21550289 - 2⁴ = 21550273 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21550283) 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 as a sum of consecutive naturals, namely, 10775144 + 10775145.

It is an arithmetic number, because the mean of its divisors is an integer number (10775145).

Almost surely, 2^21550289 is an apocalyptic number.

It is an amenable number.

21550289 is a deficient number, since it is larger than the sum of its proper divisors (1).

21550289 is an equidigital number, since it uses as much as digits as its factorization.

21550289 is an odious number, because the sum of its binary digits is odd.

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

The square root of 21550289 is about 4642.2288827674. The cubic root of 21550289 is about 278.2815195920.

The spelling of 21550289 in words is "twenty-one million, five hundred fifty thousand, two hundred eighty-nine".