21084289 has 2 divisors, whose sum is σ = 21084290. Its totient is φ = 21084288.

The previous prime is 21084269. The next prime is 21084311. The reversal of 21084289 is 98248012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20930625 + 153664 = 4575^2 + 392^2 .

It is a cyclic number.

It is not a de Polignac number, because 21084289 - 2⁵ = 21084257 is a prime.

It is not a weakly prime, because it can be changed into another prime (21084269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10542144 + 10542145.

It is an arithmetic number, because the mean of its divisors is an integer number (10542145).

Almost surely, 2^21084289 is an apocalyptic number.

It is an amenable number.

21084289 is a deficient number, since it is larger than the sum of its proper divisors (1).

21084289 is an equidigital number, since it uses as much as digits as its factorization.

21084289 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 21084289 is about 4591.7631689799. The cubic root of 21084289 is about 276.2610470388.

The spelling of 21084289 in words is "twenty-one million, eighty-four thousand, two hundred eighty-nine".