3927821 has 4 divisors (see below), whose sum is σ = 3968412. Its totient is φ = 3887232.

The previous prime is 3927769. The next prime is 3927823. The reversal of 3927821 is 1287293.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 990025 + 2937796 = 995^2 + 1714^2 .

It is a cyclic number.

It is not a de Polignac number, because 3927821 - 2¹⁸ = 3665677 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 (3927823) 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, 20150 + ... + 20343.

It is an arithmetic number, because the mean of its divisors is an integer number (992103).

Almost surely, 2^3927821 is an apocalyptic number.

It is an amenable number.

3927821 is a deficient number, since it is larger than the sum of its proper divisors (40591).

3927821 is an equidigital number, since it uses as much as digits as its factorization.

3927821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40590.

The product of its digits is 6048, while the sum is 32.

The square root of 3927821 is about 1981.8731039095. The cubic root of 3927821 is about 157.7794953232.

The spelling of 3927821 in words is "three million, nine hundred twenty-seven thousand, eight hundred twenty-one".