1191591618 has 16 divisors (see below), whose sum is σ = 2723638080. Its totient is φ = 340454736.

The previous prime is 1191591601. The next prime is 1191591641. The reversal of 1191591618 is 8161951911.

It is a Harshad number since it is a multiple of its sum of digits (42), and also a Moran number because the ratio is a prime number: 28371229 = 1191591618 / (1 + 1 + 9 + 1 + 5 + 9 + 1 + 6 + 1 + 8).

It is a self number, because there is not a number n which added to its sum of digits gives 1191591618.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14185573 + ... + 14185656.

It is an arithmetic number, because the mean of its divisors is an integer number (170227380).

Almost surely, 2^1191591618 is an apocalyptic number.

1191591618 is an abundant number, since it is smaller than the sum of its proper divisors (1532046462).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1191591618 is a wasteful number, since it uses less digits than its factorization.

1191591618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28371241.

The product of its digits is 19440, while the sum is 42.

The square root of 1191591618 is about 34519.4382631004. The cubic root of 1191591618 is about 1060.1707384873.

The spelling of 1191591618 in words is "one billion, one hundred ninety-one million, five hundred ninety-one thousand, six hundred eighteen".