20789999 has 4 divisors (see below), whose sum is σ = 21693936. Its totient is φ = 19886064.

The previous prime is 20789927. The next prime is 20790017. The reversal of 20789999 is 99998702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99998702 = 2 ⋅49999351.

It is a cyclic number.

It is not a de Polignac number, because 20789999 - 2¹⁶ = 20724463 is a prime.

It is a Duffinian number.

20789999 is a modest number, since divided by 9999 gives 2078 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 20789999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20789099) 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 in 3 ways as a sum of consecutive naturals, for example, 451934 + ... + 451979.

It is an arithmetic number, because the mean of its divisors is an integer number (5423484).

Almost surely, 2^20789999 is an apocalyptic number.

20789999 is a deficient number, since it is larger than the sum of its proper divisors (903937).

20789999 is an equidigital number, since it uses as much as digits as its factorization.

20789999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 903936.

The product of its (nonzero) digits is 734832, while the sum is 53.

The square root of 20789999 is about 4559.6051364126. The cubic root of 20789999 is about 274.9696892212.

The spelling of 20789999 in words is "twenty million, seven hundred eighty-nine thousand, nine hundred ninety-nine".