991587766 has 16 divisors (see below), whose sum is σ = 1605993984. Its totient is φ = 456456384.

The previous prime is 991587761. The next prime is 991587767. The reversal of 991587766 is 667785199.

It is a self number, because there is not a number n which added to its sum of digits gives 991587766.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991587761) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39831 + ... + 59746.

It is an arithmetic number, because the mean of its divisors is an integer number (100374624).

Almost surely, 2^991587766 is an apocalyptic number.

991587766 is the 19916-th heptagonal number.

991587766 is a deficient number, since it is larger than the sum of its proper divisors (614406218).

991587766 is a wasteful number, since it uses less digits than its factorization.

991587766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99975.

The product of its digits is 5715360, while the sum is 58.

The square root of 991587766 is about 31489.4865947351. The cubic root of 991587766 is about 997.1880221925.

The spelling of 991587766 in words is "nine hundred ninety-one million, five hundred eighty-seven thousand, seven hundred sixty-six".