21167789 has 2 divisors, whose sum is σ = 21167790. Its totient is φ = 21167788.

The previous prime is 21167747. The next prime is 21167791. The reversal of 21167789 is 98776112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18992164 + 2175625 = 4358^2 + 1475^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21167789 is a prime.

It is a super-2 number, since 2×21167789² = 896150582297042, which contains 22 as substring.

Together with 21167791, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21167189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10583894 + 10583895.

It is an arithmetic number, because the mean of its divisors is an integer number (10583895).

Almost surely, 2^21167789 is an apocalyptic number.

It is an amenable number.

21167789 is a deficient number, since it is larger than the sum of its proper divisors (1).

21167789 is an equidigital number, since it uses as much as digits as its factorization.

21167789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 42336, while the sum is 41.

The square root of 21167789 is about 4600.8465525379. The cubic root of 21167789 is about 276.6252583953.

The spelling of 21167789 in words is "twenty-one million, one hundred sixty-seven thousand, seven hundred eighty-nine".