3861821 has 2 divisors, whose sum is σ = 3861822. Its totient is φ = 3861820.

The previous prime is 3861817. The next prime is 3861841. The reversal of 3861821 is 1281683.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3204100 + 657721 = 1790^2 + 811^2 .

It is a cyclic number.

It is not a de Polignac number, because 3861821 - 2² = 3861817 is a prime.

It is a super-2 number, since 2×3861821² = 29827322872082, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is an Ulam number.

It is a Curzon number.

It is equal to p₂₇₄₀₈₈ and since 3861821 and 274088 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3861811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1930910 + 1930911.

It is an arithmetic number, because the mean of its divisors is an integer number (1930911).

Almost surely, 2^3861821 is an apocalyptic number.

It is an amenable number.

3861821 is a deficient number, since it is larger than the sum of its proper divisors (1).

3861821 is an equidigital number, since it uses as much as digits as its factorization.

3861821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2304, while the sum is 29.

The square root of 3861821 is about 1965.1516480923. The cubic root of 3861821 is about 156.8907647528.

The spelling of 3861821 in words is "three million, eight hundred sixty-one thousand, eight hundred twenty-one".