20353681 has 2 divisors, whose sum is σ = 20353682. Its totient is φ = 20353680.

The previous prime is 20353661. The next prime is 20353691. The reversal of 20353681 is 18635302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19219456 + 1134225 = 4384^2 + 1065^2 .

It is a cyclic number.

It is not a de Polignac number, because 20353681 - 2⁵ = 20353649 is a prime.

It is a super-2 number, since 2×20353681² = 828544660499522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20353651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10176840 + 10176841.

It is an arithmetic number, because the mean of its divisors is an integer number (10176841).

Almost surely, 2^20353681 is an apocalyptic number.

It is an amenable number.

20353681 is a deficient number, since it is larger than the sum of its proper divisors (1).

20353681 is an equidigital number, since it uses as much as digits as its factorization.

20353681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 20353681 is about 4511.5054028561. The cubic root of 20353681 is about 273.0324846065.

Adding to 20353681 its reverse (18635302), we get a palindrome (38988983).

The spelling of 20353681 in words is "twenty million, three hundred fifty-three thousand, six hundred eighty-one".