40905 has 20 divisors (see below), whose sum is σ = 74052. Its totient is φ = 21600.

The previous prime is 40903. The next prime is 40927. The reversal of 40905 is 50904.

Added to its reverse (50904) it gives a square (91809 = 303²).

40905 is nontrivially palindromic in base 8.

It can be written as a sum of positive squares in 2 ways, for example, as 29241 + 11664 = 171^2 + 108^2 .

It is not a de Polignac number, because 40905 - 2¹ = 40903 is a prime.

It is a nialpdrome in base 9.

It is a zygodrome in base 8.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 40905.

It is not an unprimeable number, because it can be changed into a prime (40903) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 355 + ... + 455.

2⁴⁰⁹⁰⁵ is an apocalyptic number.

40905 is a gapful number since it is divisible by the number (45) formed by its first and last digit.

It is an amenable number.

40905 is a deficient number, since it is larger than the sum of its proper divisors (33147).

40905 is a wasteful number, since it uses less digits than its factorization.

40905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118 (or 109 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 40905 is about 202.2498454882. The cubic root of 40905 is about 34.4555192353.

Adding to 40905 its reverse (50904), we get a square (91809 = 303²).

Subtracting 40905 from its reverse (50904), we obtain a palindrome (9999).

It can be divided in two parts, 4090 and 5, that added together give a triangular number (4095 = T₉₀).

The spelling of 40905 in words is "forty thousand, nine hundred five".