21668011 has 2 divisors, whose sum is σ = 21668012. Its totient is φ = 21668010.

The previous prime is 21667973. The next prime is 21668033. The reversal of 21668011 is 11086612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21668011 - 2¹⁷ = 21536939 is a prime.

It is a super-2 number, since 2×21668011² = 939005401392242, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21668111) 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, 10834005 + 10834006.

It is an arithmetic number, because the mean of its divisors is an integer number (10834006).

Almost surely, 2^21668011 is an apocalyptic number.

21668011 is a deficient number, since it is larger than the sum of its proper divisors (1).

21668011 is an equidigital number, since it uses as much as digits as its factorization.

21668011 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 21668011 is about 4654.8910835808. The cubic root of 21668011 is about 278.7873192341.

The spelling of 21668011 in words is "twenty-one million, six hundred sixty-eight thousand, eleven".