3781405 has 4 divisors (see below), whose sum is σ = 4537692. Its totient is φ = 3025120.

The previous prime is 3781403. The next prime is 3781423. The reversal of 3781405 is 5041873.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5041873 = 877 ⋅5749.

It can be written as a sum of positive squares in 2 ways, for example, as 1585081 + 2196324 = 1259^2 + 1482^2 .

It is not a de Polignac number, because 3781405 - 2¹ = 3781403 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3781403) 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, 378136 + ... + 378145.

It is an arithmetic number, because the mean of its divisors is an integer number (1134423).

Almost surely, 2^3781405 is an apocalyptic number.

It is an amenable number.

3781405 is a deficient number, since it is larger than the sum of its proper divisors (756287).

3781405 is an equidigital number, since it uses as much as digits as its factorization.

3781405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 756286.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 3781405 is about 1944.5835029641. The cubic root of 3781405 is about 155.7941208082.

It can be divided in two parts, 3781 and 405, that added together give a triangular number (4186 = T₉₁).

The spelling of 3781405 in words is "three million, seven hundred eighty-one thousand, four hundred five".