21167009 has 2 divisors, whose sum is σ = 21167010. Its totient is φ = 21167008.

The previous prime is 21166993. The next prime is 21167011. The reversal of 21167009 is 90076112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20502784 + 664225 = 4528^2 + 815^2 .

It is a cyclic number.

It is not a de Polignac number, because 21167009 - 2⁴ = 21166993 is a prime.

Together with 21167011, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1339820 and since 21167009 and 1339820 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21167099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10583504 + 10583505.

It is an arithmetic number, because the mean of its divisors is an integer number (10583505).

Almost surely, 2^21167009 is an apocalyptic number.

It is an amenable number.

21167009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21167009 is an equidigital number, since it uses as much as digits as its factorization.

21167009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 756, while the sum is 26.

The square root of 21167009 is about 4600.7617847483. The cubic root of 21167009 is about 276.6218606172.

The spelling of 21167009 in words is "twenty-one million, one hundred sixty-seven thousand, nine".