1811828561 has 2 divisors, whose sum is σ = 1811828562. Its totient is φ = 1811828560.

The previous prime is 1811828531. The next prime is 1811828587. The reversal of 1811828561 is 1658281181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1477633600 + 334194961 = 38440^2 + 18281^2 .

It is an emirp because it is prime and its reverse (1658281181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1811828561 - 2¹⁸ = 1811566417 is a prime.

It is not a weakly prime, because it can be changed into another prime (1811828531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 905914280 + 905914281.

It is an arithmetic number, because the mean of its divisors is an integer number (905914281).

Almost surely, 2^1811828561 is an apocalyptic number.

It is an amenable number.

1811828561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1811828561 is an equidigital number, since it uses as much as digits as its factorization.

1811828561 is an evil number, because the sum of its binary digits is even.

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

The square root of 1811828561 is about 42565.5795332332. The cubic root of 1811828561 is about 1219.0991650156.

The spelling of 1811828561 in words is "one billion, eight hundred eleven million, eight hundred twenty-eight thousand, five hundred sixty-one".