20506999 has 2 divisors, whose sum is σ = 20507000. Its totient is φ = 20506998.

The previous prime is 20506987. The next prime is 20507009. The reversal of 20506999 is 99960502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20506999 - 2⁹ = 20506487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20506949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10253499 + 10253500.

It is an arithmetic number, because the mean of its divisors is an integer number (10253500).

Almost surely, 2^20506999 is an apocalyptic number.

20506999 is a deficient number, since it is larger than the sum of its proper divisors (1).

20506999 is an equidigital number, since it uses as much as digits as its factorization.

20506999 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43740, while the sum is 40.

The square root of 20506999 is about 4528.4654133602. The cubic root of 20506999 is about 273.7163269049.

The spelling of 20506999 in words is "twenty million, five hundred six thousand, nine hundred ninety-nine".