991887287 has 8 divisors (see below), whose sum is σ = 1053215136. Its totient is φ = 930890752.

The previous prime is 991887271. The next prime is 991887313. The reversal of 991887287 is 782788199.

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 991887287 - 2⁴ = 991887271 is a prime.

It is a super-2 number, since 2×991887287² = 1967680780224440738, 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 (991887227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76643 + ... + 88644.

It is an arithmetic number, because the mean of its divisors is an integer number (131651892).

Almost surely, 2^991887287 is an apocalyptic number.

991887287 is a deficient number, since it is larger than the sum of its proper divisors (61327849).

991887287 is a wasteful number, since it uses less digits than its factorization.

991887287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165657.

The product of its digits is 4064256, while the sum is 59.

The square root of 991887287 is about 31494.2421245535. The cubic root of 991887287 is about 997.2884162929.

The spelling of 991887287 in words is "nine hundred ninety-one million, eight hundred eighty-seven thousand, two hundred eighty-seven".