7991216640 has 240 divisors, whose sum is σ = 30192772896. Its totient is φ = 1937203200.

The previous prime is 7991216617. The next prime is 7991216663. The reversal of 7991216640 is 466121997.

It is an interprime number because it is at equal distance from previous prime (7991216617) and next prime (7991216663).

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 237675 + ... + 269205.

Almost surely, 2^7991216640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7991216640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15096386448).

7991216640 is an abundant number, since it is smaller than the sum of its proper divisors (22201556256).

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

7991216640 is a wasteful number, since it uses less digits than its factorization.

7991216640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31571 (or 31552 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 45.

The square root of 7991216640 is about 89393.6051404126. The cubic root of 7991216640 is about 1999.2677852969.

The spelling of 7991216640 in words is "seven billion, nine hundred ninety-one million, two hundred sixteen thousand, six hundred forty".