1813726861 has 4 divisors (see below), whose sum is σ = 1818512800. Its totient is φ = 1808940924.

The previous prime is 1813726843. The next prime is 1813726891. The reversal of 1813726861 is 1686273181.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1686273181 = 8539 ⋅197479.

It is a cyclic number.

It is not a de Polignac number, because 1813726861 - 2¹⁷ = 1813595789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1813726891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2392401 + ... + 2393158.

It is an arithmetic number, because the mean of its divisors is an integer number (454628200).

Almost surely, 2^1813726861 is an apocalyptic number.

It is an amenable number.

1813726861 is a deficient number, since it is larger than the sum of its proper divisors (4785939).

1813726861 is an equidigital number, since it uses as much as digits as its factorization.

1813726861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4785938.

The product of its digits is 96768, while the sum is 43.

The square root of 1813726861 is about 42587.8722290748. The cubic root of 1813726861 is about 1219.5247770636.

The spelling of 1813726861 in words is "one billion, eight hundred thirteen million, seven hundred twenty-six thousand, eight hundred sixty-one".