20654561 has 2 divisors, whose sum is σ = 20654562. Its totient is φ = 20654560.

The previous prime is 20654551. The next prime is 20654563. The reversal of 20654561 is 16545602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16654561 + 4000000 = 4081^2 + 2000^2 .

It is a cyclic number.

It is not a de Polignac number, because 20654561 - 2¹⁰ = 20653537 is a prime.

It is a super-2 number, since 2×20654561² = 853221780205442, which contains 22 as substring.

Together with 20654563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20654563) 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, 10327280 + 10327281.

It is an arithmetic number, because the mean of its divisors is an integer number (10327281).

Almost surely, 2^20654561 is an apocalyptic number.

It is an amenable number.

20654561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20654561 is an equidigital number, since it uses as much as digits as its factorization.

20654561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7200, while the sum is 29.

The square root of 20654561 is about 4544.7289248095. The cubic root of 20654561 is about 274.3712843626.

The spelling of 20654561 in words is "twenty million, six hundred fifty-four thousand, five hundred sixty-one".