21146789 has 2 divisors, whose sum is σ = 21146790. Its totient is φ = 21146788.

The previous prime is 21146779. The next prime is 21146803. The reversal of 21146789 is 98764112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16120225 + 5026564 = 4015^2 + 2242^2 .

It is a cyclic number.

It is not a de Polignac number, because 21146789 - 2⁸ = 21146533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21146779) 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, 10573394 + 10573395.

It is an arithmetic number, because the mean of its divisors is an integer number (10573395).

Almost surely, 2^21146789 is an apocalyptic number.

It is an amenable number.

21146789 is a deficient number, since it is larger than the sum of its proper divisors (1).

21146789 is an equidigital number, since it uses as much as digits as its factorization.

21146789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 38.

The square root of 21146789 is about 4598.5637975351. The cubic root of 21146789 is about 276.5337506094.

The spelling of 21146789 in words is "twenty-one million, one hundred forty-six thousand, seven hundred eighty-nine".