20066561 has 2 divisors, whose sum is σ = 20066562. Its totient is φ = 20066560.

The previous prime is 20066539. The next prime is 20066569. The reversal of 20066561 is 16566002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12673600 + 7392961 = 3560^2 + 2719^2 .

It is a cyclic number.

It is not a de Polignac number, because 20066561 - 2¹⁰ = 20065537 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20066561.

It is not a weakly prime, because it can be changed into another prime (20066569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10033280 + 10033281.

It is an arithmetic number, because the mean of its divisors is an integer number (10033281).

Almost surely, 2^20066561 is an apocalyptic number.

It is an amenable number.

20066561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20066561 is an equidigital number, since it uses as much as digits as its factorization.

20066561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 20066561 is about 4479.5715196880. The cubic root of 20066561 is about 271.7425521422.

The spelling of 20066561 in words is "twenty million, sixty-six thousand, five hundred sixty-one".