1811720845 has 16 divisors (see below), whose sum is σ = 2405116800. Its totient is φ = 1299054400.

The previous prime is 1811720843. The next prime is 1811720863. The reversal of 1811720845 is 5480271181.

It is not a de Polignac number, because 1811720845 - 2¹ = 1811720843 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1811720843) 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 in 15 ways as a sum of consecutive naturals, for example, 228070 + ... + 235879.

It is an arithmetic number, because the mean of its divisors is an integer number (150319800).

Almost surely, 2^1811720845 is an apocalyptic number.

It is an amenable number.

1811720845 is a deficient number, since it is larger than the sum of its proper divisors (593395955).

1811720845 is a wasteful number, since it uses less digits than its factorization.

1811720845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 464036.

The product of its (nonzero) digits is 17920, while the sum is 37.

The square root of 1811720845 is about 42564.3142197781. The cubic root of 1811720845 is about 1219.0750054288.

The spelling of 1811720845 in words is "one billion, eight hundred eleven million, seven hundred twenty thousand, eight hundred forty-five".