991906784 has 24 divisors (see below), whose sum is σ = 2130346008. Its totient is φ = 450866560.

The previous prime is 991906781. The next prime is 991906813. The reversal of 991906784 is 487609199.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991906781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1408607 + ... + 1409310.

It is an arithmetic number, because the mean of its divisors is an integer number (88764417).

Almost surely, 2^991906784 is an apocalyptic number.

It is an amenable number.

991906784 is an abundant number, since it is smaller than the sum of its proper divisors (1138439224).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991906784 is a wasteful number, since it uses less digits than its factorization.

991906784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2817938 (or 2817930 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 53.

The square root of 991906784 is about 31494.5516558023. The cubic root of 991906784 is about 997.2949506392.

The spelling of 991906784 in words is "nine hundred ninety-one million, nine hundred six thousand, seven hundred eighty-four".