20309999 has 2 divisors, whose sum is σ = 20310000. Its totient is φ = 20309998.

The previous prime is 20309959. The next prime is 20310001. The reversal of 20309999 is 99990302.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20309999 is a prime.

It is a super-3 number, since 3×20309999³ (a number of 23 digits) contains 333 as substring.

Together with 20310001, it forms a pair of twin primes.

It is a Chen prime.

20309999 is a modest number, since divided by 9999 gives 2030 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20309959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10154999 + 10155000.

It is an arithmetic number, because the mean of its divisors is an integer number (10155000).

Almost surely, 2^20309999 is an apocalyptic number.

20309999 is a deficient number, since it is larger than the sum of its proper divisors (1).

20309999 is an equidigital number, since it uses as much as digits as its factorization.

20309999 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 39366, while the sum is 41.

The square root of 20309999 is about 4506.6616247506. The cubic root of 20309999 is about 272.8370220550.

The spelling of 20309999 in words is "twenty million, three hundred nine thousand, nine hundred ninety-nine".