3856409981 has 2 divisors, whose sum is σ = 3856409982. Its totient is φ = 3856409980.

The previous prime is 3856409969. The next prime is 3856409983. The reversal of 3856409981 is 1899046583.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2904132100 + 952277881 = 53890^2 + 30859^2 .

It is a cyclic number.

It is not a de Polignac number, because 3856409981 - 2¹⁰ = 3856408957 is a prime.

It is a super-2 number, since 2×3856409981² = 29743795883112840722, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 3856409983, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3856409983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1928204990 + 1928204991.

It is an arithmetic number, because the mean of its divisors is an integer number (1928204991).

Almost surely, 2^3856409981 is an apocalyptic number.

It is an amenable number.

3856409981 is a deficient number, since it is larger than the sum of its proper divisors (1).

3856409981 is an equidigital number, since it uses as much as digits as its factorization.

3856409981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1866240, while the sum is 53.

The square root of 3856409981 is about 62099.9998470209. Note that the first 3 decimals coincide. The cubic root of 3856409981 is about 1568.1745428454.

The spelling of 3856409981 in words is "three billion, eight hundred fifty-six million, four hundred nine thousand, nine hundred eighty-one".