21146549 has 2 divisors, whose sum is σ = 21146550. Its totient is φ = 21146548.

The previous prime is 21146537. The next prime is 21146551. The reversal of 21146549 is 94564112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12909649 + 8236900 = 3593^2 + 2870^2 .

It is a cyclic number.

It is not a de Polignac number, because 21146549 - 2⁴ = 21146533 is a prime.

Together with 21146551, 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 (21146519) 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, 10573274 + 10573275.

It is an arithmetic number, because the mean of its divisors is an integer number (10573275).

Almost surely, 2^21146549 is an apocalyptic number.

It is an amenable number.

21146549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21146549 is an equidigital number, since it uses as much as digits as its factorization.

21146549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8640, while the sum is 32.

The square root of 21146549 is about 4598.5377023571. The cubic root of 21146549 is about 276.5327044560.

The spelling of 21146549 in words is "twenty-one million, one hundred forty-six thousand, five hundred forty-nine".