3781821 has 12 divisors (see below), whose sum is σ = 5273408. Its totient is φ = 2410584.

The previous prime is 3781819. The next prime is 3781829. The reversal of 3781821 is 1281873.

It is a happy number.

It is not a de Polignac number, because 3781821 - 2¹ = 3781819 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3781829) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 396 + ... + 2778.

Almost surely, 2^3781821 is an apocalyptic number.

It is an amenable number.

3781821 is a deficient number, since it is larger than the sum of its proper divisors (1491587).

3781821 is a wasteful number, since it uses less digits than its factorization.

3781821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2432 (or 2409 counting only the distinct ones).

The product of its digits is 2688, while the sum is 30.

The square root of 3781821 is about 1944.6904638014. The cubic root of 3781821 is about 155.7998336740.

The spelling of 3781821 in words is "three million, seven hundred eighty-one thousand, eight hundred twenty-one".