3856921 has 2 divisors, whose sum is σ = 3856922. Its totient is φ = 3856920.

The previous prime is 3856907. The next prime is 3856949. The reversal of 3856921 is 1296583.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2368521 + 1488400 = 1539^2 + 1220^2 .

It is an emirp because it is prime and its reverse (1296583) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3856921 - 2⁷ = 3856793 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is not a weakly prime, because it can be changed into another prime (3850921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1928460 + 1928461.

It is an arithmetic number, because the mean of its divisors is an integer number (1928461).

Almost surely, 2^3856921 is an apocalyptic number.

It is an amenable number.

3856921 is a deficient number, since it is larger than the sum of its proper divisors (1).

3856921 is an equidigital number, since it uses as much as digits as its factorization.

3856921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 34.

The square root of 3856921 is about 1963.9045292478. The cubic root of 3856921 is about 156.8243806884.

The spelling of 3856921 in words is "three million, eight hundred fifty-six thousand, nine hundred twenty-one".