3943781 has 4 divisors (see below), whose sum is σ = 3948000. Its totient is φ = 3939564.

The previous prime is 3943777. The next prime is 3943799. The reversal of 3943781 is 1873493.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1873493 = 61 ⋅30713.

It is a cyclic number.

It is not a de Polignac number, because 3943781 - 2² = 3943777 is a prime.

It is a super-2 number, since 2×3943781² = 31106817151922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3943721) 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, 11 + ... + 2808.

It is an arithmetic number, because the mean of its divisors is an integer number (987000).

Almost surely, 2^3943781 is an apocalyptic number.

It is an amenable number.

3943781 is a deficient number, since it is larger than the sum of its proper divisors (4219).

3943781 is a wasteful number, since it uses less digits than its factorization.

3943781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4218.

The product of its digits is 18144, while the sum is 35.

The square root of 3943781 is about 1985.8955158819. The cubic root of 3943781 is about 157.9929094719.

The spelling of 3943781 in words is "three million, nine hundred forty-three thousand, seven hundred eighty-one".