21068869 has 2 divisors, whose sum is σ = 21068870. Its totient is φ = 21068868.

The previous prime is 21068867. The next prime is 21068893. The reversal of 21068869 is 96886012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12687844 + 8381025 = 3562^2 + 2895^2 .

It is a cyclic number.

It is not a de Polignac number, because 21068869 - 2¹ = 21068867 is a prime.

It is a super-2 number, since 2×21068869² = 887794481878322, which contains 22 as substring.

Together with 21068867, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21068867) 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, 10534434 + 10534435.

It is an arithmetic number, because the mean of its divisors is an integer number (10534435).

Almost surely, 2^21068869 is an apocalyptic number.

It is an amenable number.

21068869 is a deficient number, since it is larger than the sum of its proper divisors (1).

21068869 is an equidigital number, since it uses as much as digits as its factorization.

21068869 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 41472, while the sum is 40.

The square root of 21068869 is about 4590.0837682988. The cubic root of 21068869 is about 276.1936827521.

The spelling of 21068869 in words is "twenty-one million, sixty-eight thousand, eight hundred sixty-nine".