20198905 has 4 divisors (see below), whose sum is σ = 24238692. Its totient is φ = 16159120.

The previous prime is 20198903. The next prime is 20198911. The reversal of 20198905 is 50989102.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2424249 + 17774656 = 1557^2 + 4216^2 .

It is not a de Polignac number, because 20198905 - 2¹ = 20198903 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20198903) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2019886 + ... + 2019895.

It is an arithmetic number, because the mean of its divisors is an integer number (6059673).

Almost surely, 2^20198905 is an apocalyptic number.

It is an amenable number.

20198905 is a deficient number, since it is larger than the sum of its proper divisors (4039787).

20198905 is an equidigital number, since it uses as much as digits as its factorization.

20198905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4039786.

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 20198905 is about 4494.3191920468. The cubic root of 20198905 is about 272.3386470084.

The spelling of 20198905 in words is "twenty million, one hundred ninety-eight thousand, nine hundred five".