1851861281 has 2 divisors, whose sum is σ = 1851861282. Its totient is φ = 1851861280.

The previous prime is 1851861259. The next prime is 1851861293. The reversal of 1851861281 is 1821681581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1830470656 + 21390625 = 42784^2 + 4625^2 .

It is a cyclic number.

It is not a de Polignac number, because 1851861281 - 2⁶ = 1851861217 is a prime.

It is a super-2 number, since 2×1851861281² = 6858780408133921922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1851861481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 925930640 + 925930641.

It is an arithmetic number, because the mean of its divisors is an integer number (925930641).

Almost surely, 2^1851861281 is an apocalyptic number.

It is an amenable number.

1851861281 is a deficient number, since it is larger than the sum of its proper divisors (1).

1851861281 is an equidigital number, since it uses as much as digits as its factorization.

1851861281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30720, while the sum is 41.

The square root of 1851861281 is about 43033.2578478553. The cubic root of 1851861281 is about 1228.0125837800.

The spelling of 1851861281 in words is "one billion, eight hundred fifty-one million, eight hundred sixty-one thousand, two hundred eighty-one".