1918291891 has 4 divisors (see below), whose sum is σ = 1921663800. Its totient is φ = 1914919984.

The previous prime is 1918291867. The next prime is 1918291909. The reversal of 1918291891 is 1981928191.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1918291891 - 2¹³ = 1918283699 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1918292891) 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 3 ways as a sum of consecutive naturals, for example, 1685101 + ... + 1686238.

It is an arithmetic number, because the mean of its divisors is an integer number (480415950).

Almost surely, 2^1918291891 is an apocalyptic number.

1918291891 is a deficient number, since it is larger than the sum of its proper divisors (3371909).

1918291891 is an equidigital number, since it uses as much as digits as its factorization.

1918291891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3371908.

The product of its digits is 93312, while the sum is 49.

The square root of 1918291891 is about 43798.3092253571. The cubic root of 1918291891 is about 1242.5243172075.

The spelling of 1918291891 in words is "one billion, nine hundred eighteen million, two hundred ninety-one thousand, eight hundred ninety-one".