21080869 has 2 divisors, whose sum is σ = 21080870. Its totient is φ = 21080868.

The previous prime is 21080849. The next prime is 21080887. The reversal of 21080869 is 96808012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 12769 = 4590^2 + 113^2 .

It is a cyclic number.

It is not a de Polignac number, because 21080869 - 2¹³ = 21072677 is a prime.

It is a super-2 number, since 2×21080869² = 888806075590322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21080849) 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, 10540434 + 10540435.

It is an arithmetic number, because the mean of its divisors is an integer number (10540435).

Almost surely, 2^21080869 is an apocalyptic number.

It is an amenable number.

21080869 is a deficient number, since it is larger than the sum of its proper divisors (1).

21080869 is an equidigital number, since it uses as much as digits as its factorization.

21080869 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 21080869 is about 4591.3907479107. The cubic root of 21080869 is about 276.2461091567.

The spelling of 21080869 in words is "twenty-one million, eighty thousand, eight hundred sixty-nine".