20231905 has 4 divisors (see below), whose sum is σ = 24278292. Its totient is φ = 16185520.

The previous prime is 20231873. The next prime is 20231909. The reversal of 20231905 is 50913202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50913202 = 2 ⋅25456601.

It can be written as a sum of positive squares in 2 ways, for example, as 5239521 + 14992384 = 2289^2 + 3872^2 .

It is not a de Polignac number, because 20231905 - 2⁵ = 20231873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20231909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2023186 + ... + 2023195.

It is an arithmetic number, because the mean of its divisors is an integer number (6069573).

Almost surely, 2^20231905 is an apocalyptic number.

It is an amenable number.

20231905 is a deficient number, since it is larger than the sum of its proper divisors (4046387).

20231905 is an equidigital number, since it uses as much as digits as its factorization.

20231905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4046386.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 20231905 is about 4497.9889950955. The cubic root of 20231905 is about 272.4868775770.

The spelling of 20231905 in words is "twenty million, two hundred thirty-one thousand, nine hundred five".