3985167821 has 2 divisors, whose sum is σ = 3985167822. Its totient is φ = 3985167820.

The previous prime is 3985167817. The next prime is 3985167827. The reversal of 3985167821 is 1287615893.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2917512196 + 1067655625 = 54014^2 + 32675^2 .

It is an emirp because it is prime and its reverse (1287615893) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3985167821 - 2² = 3985167817 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 3985167821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3985167827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1992583910 + 1992583911.

It is an arithmetic number, because the mean of its divisors is an integer number (1992583911).

Almost surely, 2^3985167821 is an apocalyptic number.

It is an amenable number.

3985167821 is a deficient number, since it is larger than the sum of its proper divisors (1).

3985167821 is an equidigital number, since it uses as much as digits as its factorization.

3985167821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 725760, while the sum is 50.

The square root of 3985167821 is about 63128.1856305090. The cubic root of 3985167821 is about 1585.4365704563.

The spelling of 3985167821 in words is "three billion, nine hundred eighty-five million, one hundred sixty-seven thousand, eight hundred twenty-one".