3781955561 has 2 divisors, whose sum is σ = 3781955562. Its totient is φ = 3781955560.

The previous prime is 3781955549. The next prime is 3781955581. The reversal of 3781955561 is 1655591873.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3053225536 + 728730025 = 55256^2 + 26995^2 .

It is a cyclic number.

It is not a de Polignac number, because 3781955561 - 2¹⁰ = 3781954537 is a prime.

It is not a weakly prime, because it can be changed into another prime (3781955581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1890977780 + 1890977781.

It is an arithmetic number, because the mean of its divisors is an integer number (1890977781).

Almost surely, 2^3781955561 is an apocalyptic number.

It is an amenable number.

3781955561 is a deficient number, since it is larger than the sum of its proper divisors (1).

3781955561 is an equidigital number, since it uses as much as digits as its factorization.

3781955561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1134000, while the sum is 50.

The square root of 3781955561 is about 61497.6061404019. The cubic root of 3781955561 is about 1558.0168149041.

The spelling of 3781955561 in words is "three billion, seven hundred eighty-one million, nine hundred fifty-five thousand, five hundred sixty-one".