6191665921 has 12 divisors (see below), whose sum is σ = 7207742340. Its totient is φ = 5303316480.

The previous prime is 6191665853. The next prime is 6191665937. The reversal of 6191665921 is 1295661916.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 1524043521 + 4667622400 = 39039^2 + 68320^2 .

It is not a de Polignac number, because 6191665921 - 2⁹ = 6191665409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6191665621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 24201 + ... + 113881.

It is an arithmetic number, because the mean of its divisors is an integer number (600645195).

Almost surely, 2^6191665921 is an apocalyptic number.

It is an amenable number.

6191665921 is a deficient number, since it is larger than the sum of its proper divisors (1016076419).

6191665921 is a wasteful number, since it uses less digits than its factorization.

6191665921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91104 (or 91097 counting only the distinct ones).

The product of its digits is 174960, while the sum is 46.

The square root of 6191665921 is about 78687.1394892456. The cubic root of 6191665921 is about 1836.2670380229.

The spelling of 6191665921 in words is "six billion, one hundred ninety-one million, six hundred sixty-five thousand, nine hundred twenty-one".