3940021 has 2 divisors, whose sum is σ = 3940022. Its totient is φ = 3940020.

The previous prime is 3940009. The next prime is 3940033. The reversal of 3940021 is 1200493.

It is a balanced prime because it is at equal distance from previous prime (3940009) and next prime (3940033).

It can be written as a sum of positive squares in only one way, i.e., 2592100 + 1347921 = 1610^2 + 1161^2 .

It is a cyclic number.

It is not a de Polignac number, because 3940021 - 2⁵ = 3939989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3940091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1970010 + 1970011.

It is an arithmetic number, because the mean of its divisors is an integer number (1970011).

Almost surely, 2^3940021 is an apocalyptic number.

It is an amenable number.

3940021 is a deficient number, since it is larger than the sum of its proper divisors (1).

3940021 is an equidigital number, since it uses as much as digits as its factorization.

3940021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 3940021 is about 1984.9486139445. The cubic root of 3940021 is about 157.9426833708.

The spelling of 3940021 in words is "three million, nine hundred forty thousand, twenty-one".