3936821 has 4 divisors (see below), whose sum is σ = 4499232. Its totient is φ = 3374412.

The previous prime is 3936811. The next prime is 3936827. The reversal of 3936821 is 1286393.

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 an emirpimes, since its reverse is a distinct semiprime: 1286393 = 233 ⋅5521.

It is a cyclic number.

It is not a de Polignac number, because 3936821 - 2¹⁰ = 3935797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3936827) 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, 281195 + ... + 281208.

It is an arithmetic number, because the mean of its divisors is an integer number (1124808).

Almost surely, 2^3936821 is an apocalyptic number.

It is an amenable number.

3936821 is a deficient number, since it is larger than the sum of its proper divisors (562411).

3936821 is an equidigital number, since it uses as much as digits as its factorization.

3936821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562410.

The product of its digits is 7776, while the sum is 32.

The square root of 3936821 is about 1984.1423840037. The cubic root of 3936821 is about 157.8999125769.

The spelling of 3936821 in words is "three million, nine hundred thirty-six thousand, eight hundred twenty-one".