20399993 has 2 divisors, whose sum is σ = 20399994. Its totient is φ = 20399992.

The previous prime is 20399969. The next prime is 20400013. The reversal of 20399993 is 39999302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19035769 + 1364224 = 4363^2 + 1168^2 .

It is a cyclic number.

It is not a de Polignac number, because 20399993 - 2⁸ = 20399737 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20399593) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10199996 + 10199997.

It is an arithmetic number, because the mean of its divisors is an integer number (10199997).

Almost surely, 2^20399993 is an apocalyptic number.

It is an amenable number.

20399993 is a deficient number, since it is larger than the sum of its proper divisors (1).

20399993 is an equidigital number, since it uses as much as digits as its factorization.

20399993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 118098, while the sum is 44.

The square root of 20399993 is about 4516.6351413414. The cubic root of 20399993 is about 273.2394103566.

The spelling of 20399993 in words is "twenty million, three hundred ninety-nine thousand, nine hundred ninety-three".