1905 has 8 divisors (see below), whose sum is σ = 3072. Its totient is φ = 1008.

The previous prime is 1901. The next prime is 1907. The reversal of 1905 is 5091.

1905 = 9² + 10² + ... + 18².

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1905 - 2² = 1901 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15), and also a Moran number because the ratio is a prime number: 127 = 1905 / (1 + 9 + 0 + 5).

It is a plaindrome in base 12.

It is a nialpdrome in base 15 and base 16.

It is not an unprimeable number, because it can be changed into a prime (1901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49 + ... + 78.

It is an arithmetic number, because the mean of its divisors is an integer number (384).

It is a Poulet number, since it divides 2¹⁹⁰⁴-1.

1905 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1905 is a deficient number, since it is larger than the sum of its proper divisors (1167).

1905 is a wasteful number, since it uses less digits than its factorization.

1905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135.

The product of its (nonzero) digits is 45, while the sum is 15.

The square root of 1905 is about 43.6463056856. The cubic root of 1905 is about 12.3964783617.

Adding to 1905 its reverse (5091), we get a palindrome (6996).

The spelling of 1905 in words is "one thousand, nine hundred five".