20353721 has 2 divisors, whose sum is σ = 20353722. Its totient is φ = 20353720.

The previous prime is 20353703. The next prime is 20353733. The reversal of 20353721 is 12735302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16605625 + 3748096 = 4075^2 + 1936^2 .

It is a cyclic number.

It is not a de Polignac number, because 20353721 - 2⁶ = 20353657 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20353741) 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, 10176860 + 10176861.

It is an arithmetic number, because the mean of its divisors is an integer number (10176861).

Almost surely, 2^20353721 is an apocalyptic number.

It is an amenable number.

20353721 is a deficient number, since it is larger than the sum of its proper divisors (1).

20353721 is an equidigital number, since it uses as much as digits as its factorization.

20353721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 20353721 is about 4511.5098359640. The cubic root of 20353721 is about 273.0326634651.

The spelling of 20353721 in words is "twenty million, three hundred fifty-three thousand, seven hundred twenty-one".