20109999 has 32 divisors (see below), whose sum is σ = 34746880. Its totient is φ = 10046592.

The previous prime is 20109989. The next prime is 20110043. The reversal of 20109999 is 99990102.

It is a happy number.

It is not a de Polignac number, because 20109999 - 2⁷ = 20109871 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

20109999 is a modest number, since divided by 9999 gives 2010 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20109989) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3249 + ... + 7125.

It is an arithmetic number, because the mean of its divisors is an integer number (1085840).

Almost surely, 2^20109999 is an apocalyptic number.

20109999 is a deficient number, since it is larger than the sum of its proper divisors (14636881).

20109999 is a wasteful number, since it uses less digits than its factorization.

20109999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3919.

The product of its (nonzero) digits is 13122, while the sum is 39.

The square root of 20109999 is about 4484.4173534585. The cubic root of 20109999 is about 271.9384908133.

The spelling of 20109999 in words is "twenty million, one hundred nine thousand, nine hundred ninety-nine".