20728061 has 2 divisors, whose sum is σ = 20728062. Its totient is φ = 20728060.

The previous prime is 20728033. The next prime is 20728063. The reversal of 20728061 is 16082702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17556100 + 3171961 = 4190^2 + 1781^2 .

It is a cyclic number.

It is not a de Polignac number, because 20728061 - 2¹⁰ = 20727037 is a prime.

Together with 20728063, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20728061.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20728063) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10364030 + 10364031.

It is an arithmetic number, because the mean of its divisors is an integer number (10364031).

Almost surely, 2^20728061 is an apocalyptic number.

It is an amenable number.

20728061 is a deficient number, since it is larger than the sum of its proper divisors (1).

20728061 is an equidigital number, since it uses as much as digits as its factorization.

20728061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 20728061 is about 4552.8080346090. The cubic root of 20728061 is about 274.6963524473.

The spelling of 20728061 in words is "twenty million, seven hundred twenty-eight thousand, sixty-one".