1191920091 has 4 divisors (see below), whose sum is σ = 1589226792. Its totient is φ = 794613392.

The previous prime is 1191920087. The next prime is 1191920131. The reversal of 1191920091 is 1900291911.

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 1191920091 - 2² = 1191920087 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1191920071) 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, 198653346 + ... + 198653351.

It is an arithmetic number, because the mean of its divisors is an integer number (397306698).

Almost surely, 2^1191920091 is an apocalyptic number.

1191920091 is a deficient number, since it is larger than the sum of its proper divisors (397306701).

1191920091 is an equidigital number, since it uses as much as digits as its factorization.

1191920091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397306700.

The product of its (nonzero) digits is 1458, while the sum is 33.

The square root of 1191920091 is about 34524.1957328480. The cubic root of 1191920091 is about 1060.2681447531.

The spelling of 1191920091 in words is "one billion, one hundred ninety-one million, nine hundred twenty thousand, ninety-one".