191121997 has 8 divisors (see below), whose sum is σ = 210562272. Its totient is φ = 172026000.

The previous prime is 191121991. The next prime is 191122003. The reversal of 191121997 is 799121191.

It is an interprime number because it is at equal distance from previous prime (191121991) and next prime (191122003).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 191121997 - 2²³ = 182733389 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 (191121991) 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 7 ways as a sum of consecutive naturals, for example, 84903 + ... + 87124.

It is an arithmetic number, because the mean of its divisors is an integer number (26320284).

Almost surely, 2^191121997 is an apocalyptic number.

It is an amenable number.

191121997 is a deficient number, since it is larger than the sum of its proper divisors (19440275).

191121997 is a wasteful number, since it uses less digits than its factorization.

191121997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172139.

The product of its digits is 10206, while the sum is 40.

The square root of 191121997 is about 13824.6879530787. The cubic root of 191121997 is about 576.0191096492.

The spelling of 191121997 in words is "one hundred ninety-one million, one hundred twenty-one thousand, nine hundred ninety-seven".