391115887 has 4 divisors (see below), whose sum is σ = 391519656. Its totient is φ = 390712120.

The previous prime is 391115873. The next prime is 391115927. The reversal of 391115887 is 788511193.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-391115887 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 (391115287) 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, 200428 + ... + 202369.

It is an arithmetic number, because the mean of its divisors is an integer number (97879914).

Almost surely, 2^391115887 is an apocalyptic number.

391115887 is a deficient number, since it is larger than the sum of its proper divisors (403769).

391115887 is an equidigital number, since it uses as much as digits as its factorization.

391115887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403768.

The product of its digits is 60480, while the sum is 43.

The square root of 391115887 is about 19776.6500449394. The cubic root of 391115887 is about 731.3105169971.

The spelling of 391115887 in words is "three hundred ninety-one million, one hundred fifteen thousand, eight hundred eighty-seven".