2051781857 has 2 divisors, whose sum is σ = 2051781858. Its totient is φ = 2051781856.

The previous prime is 2051781847. The next prime is 2051781877. The reversal of 2051781857 is 7581871502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1558986256 + 492795601 = 39484^2 + 22199^2 .

It is a cyclic number.

It is not a de Polignac number, because 2051781857 - 2¹⁶ = 2051716321 is a prime.

It is not a weakly prime, because it can be changed into another prime (2051781827) 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, 1025890928 + 1025890929.

It is an arithmetic number, because the mean of its divisors is an integer number (1025890929).

Almost surely, 2^2051781857 is an apocalyptic number.

It is an amenable number.

2051781857 is a deficient number, since it is larger than the sum of its proper divisors (1).

2051781857 is an equidigital number, since it uses as much as digits as its factorization.

2051781857 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 156800, while the sum is 44.

The square root of 2051781857 is about 45296.5987354459. The cubic root of 2051781857 is about 1270.7020436971.

The spelling of 2051781857 in words is "two billion, fifty-one million, seven hundred eighty-one thousand, eight hundred fifty-seven".