1405 has 4 divisors (see below), whose sum is σ = 1692. Its totient is φ = 1120.

The previous prime is 1399. The next prime is 1409. The reversal of 1405 is 5041.

1405 = 7² + 8² + ... + 16².

1405 is nontrivially palindromic in base 6.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5041 = 71².

It can be written as a sum of positive squares in 2 ways, for example, as 729 + 676 = 27^2 + 26^2 .

It is not a de Polignac number, because 1405 - 2⁵ = 1373 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a nialpdrome in base 5, base 12 and base 13.

It is a junction number, because it is equal to n+sod(n) for n = 1391 and 1400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1409) 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, 136 + ... + 145.

It is an arithmetic number, because the mean of its divisors is an integer number (423).

1405 is the 27-th centered square number.

It is an amenable number.

1405 is a deficient number, since it is larger than the sum of its proper divisors (287).

1405 is an equidigital number, since it uses as much as digits as its factorization.

1405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 286.

The product of its (nonzero) digits is 20, while the sum is 10.

The square root of 1405 is about 37.4833296280. The cubic root of 1405 is about 11.2001913233.

Adding to 1405 its reverse (5041), we get a palindrome (6446).

It can be divided in two parts, 1 and 405, that added together give a triangular number (406 = T₂₈).

The spelling of 1405 in words is "one thousand, four hundred five".