6991151668 has 24 divisors (see below), whose sum is σ = 12794221440. Its totient is φ = 3336321120.

The previous prime is 6991151647. The next prime is 6991151683. The reversal of 6991151668 is 8661511996.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40008 + ... + 124831.

It is an arithmetic number, because the mean of its divisors is an integer number (533092560).

Almost surely, 2^6991151668 is an apocalyptic number.

It is an amenable number.

6991151668 is a deficient number, since it is larger than the sum of its proper divisors (5803069772).

6991151668 is a wasteful number, since it uses less digits than its factorization.

6991151668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165327 (or 165325 counting only the distinct ones).

The product of its digits is 699840, while the sum is 52.

The square root of 6991151668 is about 83613.1070347227. The cubic root of 6991151668 is about 1912.1248310071.

The spelling of 6991151668 in words is "six billion, nine hundred ninety-one million, one hundred fifty-one thousand, six hundred sixty-eight".