766391991 has 8 divisors (see below), whose sum is σ = 1022025984. Its totient is φ = 510843000.

The previous prime is 766391987. The next prime is 766392023. The reversal of 766391991 is 199193667.

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

It is not a de Polignac number, because 766391991 - 2² = 766391987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (766391911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4116 + ... + 39366.

It is an arithmetic number, because the mean of its divisors is an integer number (127753248).

Almost surely, 2^766391991 is an apocalyptic number.

766391991 is a deficient number, since it is larger than the sum of its proper divisors (255633993).

766391991 is a wasteful number, since it uses less digits than its factorization.

766391991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42501.

The product of its digits is 551124, while the sum is 51.

The square root of 766391991 is about 27683.7857057159. The cubic root of 766391991 is about 915.1318117611.

The spelling of 766391991 in words is "seven hundred sixty-six million, three hundred ninety-one thousand, nine hundred ninety-one".