991916641 has 16 divisors (see below), whose sum is σ = 1081036800. Its totient is φ = 906670800.

The previous prime is 991916593. The next prime is 991916687. The reversal of 991916641 is 146619199.

It is a cyclic number.

It is not a de Polignac number, because 991916641 - 2¹¹ = 991914593 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 991916591 and 991916600.

It is not an unprimeable number, because it can be changed into a prime (991913641) 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 15 ways as a sum of consecutive naturals, for example, 209106 + ... + 213796.

It is an arithmetic number, because the mean of its divisors is an integer number (67564800).

Almost surely, 2^991916641 is an apocalyptic number.

It is an amenable number.

991916641 is a deficient number, since it is larger than the sum of its proper divisors (89120159).

991916641 is a wasteful number, since it uses less digits than its factorization.

991916641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5100.

The product of its digits is 104976, while the sum is 46.

The square root of 991916641 is about 31494.7081427976. The cubic root of 991916641 is about 997.2982541431.

The spelling of 991916641 in words is "nine hundred ninety-one million, nine hundred sixteen thousand, six hundred forty-one".