18991814357 has 4 divisors (see below), whose sum is σ = 19817545440. Its totient is φ = 18166083276.

The previous prime is 18991814351. The next prime is 18991814383. The reversal of 18991814357 is 75341819981.

It is a happy number.

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 18991814357 - 2⁶ = 18991814293 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 (18991814351) 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, 412865507 + ... + 412865552.

It is an arithmetic number, because the mean of its divisors is an integer number (4954386360).

Almost surely, 2^18991814357 is an apocalyptic number.

It is an amenable number.

18991814357 is a deficient number, since it is larger than the sum of its proper divisors (825731083).

18991814357 is an equidigital number, since it uses as much as digits as its factorization.

18991814357 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 825731082.

The product of its digits is 2177280, while the sum is 56.

The spelling of 18991814357 in words is "eighteen billion, nine hundred ninety-one million, eight hundred fourteen thousand, three hundred fifty-seven".