3911821 has 2 divisors, whose sum is σ = 3911822. Its totient is φ = 3911820.

The previous prime is 3911807. The next prime is 3911849. The reversal of 3911821 is 1281193.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3759721 + 152100 = 1939^2 + 390^2 .

It is an emirp because it is prime and its reverse (1281193) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3911821 - 2⁷ = 3911693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3911861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1955910 + 1955911.

It is an arithmetic number, because the mean of its divisors is an integer number (1955911).

Almost surely, 2^3911821 is an apocalyptic number.

It is an amenable number.

3911821 is a deficient number, since it is larger than the sum of its proper divisors (1).

3911821 is an equidigital number, since it uses as much as digits as its factorization.

3911821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432, while the sum is 25.

The square root of 3911821 is about 1977.8323993706. The cubic root of 3911821 is about 157.5649652211.

The spelling of 3911821 in words is "three million, nine hundred eleven thousand, eight hundred twenty-one".