20503999 has 2 divisors, whose sum is σ = 20504000. Its totient is φ = 20503998.

The previous prime is 20503997. The next prime is 20504009. The reversal of 20503999 is 99930502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20503999 - 2¹ = 20503997 is a prime.

Together with 20503997, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20503993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10251999 + 10252000.

It is an arithmetic number, because the mean of its divisors is an integer number (10252000).

Almost surely, 2^20503999 is an apocalyptic number.

20503999 is a deficient number, since it is larger than the sum of its proper divisors (1).

20503999 is an equidigital number, since it uses as much as digits as its factorization.

20503999 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21870, while the sum is 37.

The square root of 20503999 is about 4528.1341632067. The cubic root of 20503999 is about 273.7029787951.

The spelling of 20503999 in words is "twenty million, five hundred three thousand, nine hundred ninety-nine".