191397887 has 4 divisors (see below), whose sum is σ = 201471480. Its totient is φ = 181324296.

The previous prime is 191397851. The next prime is 191397919. The reversal of 191397887 is 788793191.

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

It is not a de Polignac number, because 191397887 - 2¹² = 191393791 is a prime.

It is a super-2 number, since 2×191397887² = 73266302296129538, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191397827) 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, 5036768 + ... + 5036805.

It is an arithmetic number, because the mean of its divisors is an integer number (50367870).

Almost surely, 2^191397887 is an apocalyptic number.

191397887 is a deficient number, since it is larger than the sum of its proper divisors (10073593).

191397887 is a wasteful number, since it uses less digits than its factorization.

191397887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10073592.

The product of its digits is 762048, while the sum is 53.

The square root of 191397887 is about 13834.6625184715. The cubic root of 191397887 is about 576.2961430074.

The spelling of 191397887 in words is "one hundred ninety-one million, three hundred ninety-seven thousand, eight hundred eighty-seven".