7921663680 has 448 divisors, whose sum is σ = 30337597440. Its totient is φ = 1712173056.

The previous prime is 7921663649. The next prime is 7921663681. The reversal of 7921663680 is 863661297.

It is a tau number, because it is divible by the number of its divisors (448).

It is a super-2 number, since 2×7921663680² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (7921663681) 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 63 ways as a sum of consecutive naturals, for example, 16537681 + ... + 16538159.

Almost surely, 2^7921663680 is an apocalyptic number.

7921663680 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7921663680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15168798720).

7921663680 is an abundant number, since it is smaller than the sum of its proper divisors (22415933760).

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

7921663680 is a wasteful number, since it uses less digits than its factorization.

7921663680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 636 (or 626 counting only the distinct ones).

The product of its (nonzero) digits is 653184, while the sum is 48.

The square root of 7921663680 is about 89003.7284612280. The cubic root of 7921663680 is about 1993.4505490915.

The spelling of 7921663680 in words is "seven billion, nine hundred twenty-one million, six hundred sixty-three thousand, six hundred eighty".