1863991813 has 4 divisors (see below), whose sum is σ = 1864771200. Its totient is φ = 1863212428.

The previous prime is 1863991799. The next prime is 1863991819. The reversal of 1863991813 is 3181993681.

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.

It is a cyclic number.

It is not a de Polignac number, because 1863991813 - 2²⁵ = 1830437381 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 (1863991819) 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 in 3 ways as a sum of consecutive naturals, for example, 386095 + ... + 390892.

It is an arithmetic number, because the mean of its divisors is an integer number (466192800).

Almost surely, 2^1863991813 is an apocalyptic number.

It is an amenable number.

1863991813 is a deficient number, since it is larger than the sum of its proper divisors (779387).

1863991813 is an equidigital number, since it uses as much as digits as its factorization.

1863991813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 779386.

The product of its digits is 279936, while the sum is 49.

The square root of 1863991813 is about 43173.9714758788. The cubic root of 1863991813 is about 1230.6880969314.

The spelling of 1863991813 in words is "one billion, eight hundred sixty-three million, nine hundred ninety-one thousand, eight hundred thirteen".