7991644816 has 15 divisors (see below), whose sum is σ = 15484504681. Its totient is φ = 3995643616.

The previous prime is 7991644789. The next prime is 7991644841. The reversal of 7991644816 is 6184461997.

The square root of 7991644816 is 89396.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 1267644816 + 6724000000 = 35604^2 + 82000^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 346410 + ... + 368758.

Almost surely, 2^7991644816 is an apocalyptic number.

7991644816 is the 89396-th square number.

It is an amenable number.

7991644816 is a deficient number, since it is larger than the sum of its proper divisors (7492859865).

7991644816 is an frugal number, since it uses more digits than its factorization.

7991644816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44706 (or 22351 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 55.

The cubic root of 7991644816 is about 1999.3034921332.

The spelling of 7991644816 in words is "seven billion, nine hundred ninety-one million, six hundred forty-four thousand, eight hundred sixteen".