20388449 has 2 divisors, whose sum is σ = 20388450. Its totient is φ = 20388448.

The previous prime is 20388437. The next prime is 20388451. The reversal of 20388449 is 94488302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17698849 + 2689600 = 4207^2 + 1640^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20388449 is a prime.

It is a Sophie Germain prime.

Together with 20388451, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20388409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10194224 + 10194225.

It is an arithmetic number, because the mean of its divisors is an integer number (10194225).

Almost surely, 2^20388449 is an apocalyptic number.

It is an amenable number.

20388449 is a deficient number, since it is larger than the sum of its proper divisors (1).

20388449 is an equidigital number, since it uses as much as digits as its factorization.

20388449 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 55296, while the sum is 38.

The square root of 20388449 is about 4515.3570179998. The cubic root of 20388449 is about 273.1878601604.

The spelling of 20388449 in words is "twenty million, three hundred eighty-eight thousand, four hundred forty-nine".