3878921 has 2 divisors, whose sum is σ = 3878922. Its totient is φ = 3878920.

The previous prime is 3878899. The next prime is 3878923. The reversal of 3878921 is 1298783.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2805625 + 1073296 = 1675^2 + 1036^2 .

It is a cyclic number.

It is not a de Polignac number, because 3878921 - 2¹⁰ = 3877897 is a prime.

Together with 3878923, it forms a pair of twin primes.

It is a Chen prime.

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

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3878923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1939460 + 1939461.

It is an arithmetic number, because the mean of its divisors is an integer number (1939461).

Almost surely, 2^3878921 is an apocalyptic number.

It is an amenable number.

3878921 is a deficient number, since it is larger than the sum of its proper divisors (1).

3878921 is an equidigital number, since it uses as much as digits as its factorization.

3878921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 38.

The square root of 3878921 is about 1969.4976516868. The cubic root of 3878921 is about 157.1219926254.

The spelling of 3878921 in words is "three million, eight hundred seventy-eight thousand, nine hundred twenty-one".