20505799 has 2 divisors, whose sum is σ = 20505800. Its totient is φ = 20505798.

The previous prime is 20505761. The next prime is 20505803. The reversal of 20505799 is 99750502.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20505799 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20505599) 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, 10252899 + 10252900.

It is an arithmetic number, because the mean of its divisors is an integer number (10252900).

Almost surely, 2^20505799 is an apocalyptic number.

20505799 is a deficient number, since it is larger than the sum of its proper divisors (1).

20505799 is an equidigital number, since it uses as much as digits as its factorization.

20505799 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28350, while the sum is 37.

The square root of 20505799 is about 4528.3329162066. The cubic root of 20505799 is about 273.7109878172.

The spelling of 20505799 in words is "twenty million, five hundred five thousand, seven hundred ninety-nine".