20561369 has 2 divisors, whose sum is σ = 20561370. Its totient is φ = 20561368.

The previous prime is 20561351. The next prime is 20561407. The reversal of 20561369 is 96316502.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13053769 + 7507600 = 3613^2 + 2740^2 .

It is a cyclic number.

It is not a de Polignac number, because 20561369 - 2⁸ = 20561113 is a prime.

It is a super-2 number, since 2×20561369² = 845539790308322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20561329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10280684 + 10280685.

It is an arithmetic number, because the mean of its divisors is an integer number (10280685).

Almost surely, 2^20561369 is an apocalyptic number.

It is an amenable number.

20561369 is a deficient number, since it is larger than the sum of its proper divisors (1).

20561369 is an equidigital number, since it uses as much as digits as its factorization.

20561369 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9720, while the sum is 32.

The square root of 20561369 is about 4534.4645769925. The cubic root of 20561369 is about 273.9580138838.

The spelling of 20561369 in words is "twenty million, five hundred sixty-one thousand, three hundred sixty-nine".