20728549 has 2 divisors, whose sum is σ = 20728550. Its totient is φ = 20728548.

The previous prime is 20728531. The next prime is 20728571. The reversal of 20728549 is 94582702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18748900 + 1979649 = 4330^2 + 1407^2 .

It is a cyclic number.

It is not a de Polignac number, because 20728549 - 2⁵ = 20728517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20728579) 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, 10364274 + 10364275.

It is an arithmetic number, because the mean of its divisors is an integer number (10364275).

Almost surely, 2^20728549 is an apocalyptic number.

It is an amenable number.

20728549 is a deficient number, since it is larger than the sum of its proper divisors (1).

20728549 is an equidigital number, since it uses as much as digits as its factorization.

20728549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40320, while the sum is 37.

The square root of 20728549 is about 4552.8616275920. The cubic root of 20728549 is about 274.6985081525.

The spelling of 20728549 in words is "twenty million, seven hundred twenty-eight thousand, five hundred forty-nine".