7947921640 has 16 divisors (see below), whose sum is σ = 17882823780. Its totient is φ = 3179168640.

The previous prime is 7947921623. The next prime is 7947921643. The reversal of 7947921640 is 461297497.

It can be written as a sum of positive squares in 2 ways, for example, as 6480572004 + 1467349636 = 80502^2 + 38306^2 .

It is not an unprimeable number, because it can be changed into a prime (7947921643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99348981 + ... + 99349060.

Almost surely, 2^7947921640 is an apocalyptic number.

It is an amenable number.

7947921640 is an abundant number, since it is smaller than the sum of its proper divisors (9934902140).

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

7947921640 is a wasteful number, since it uses less digits than its factorization.

7947921640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198698052 (or 198698048 counting only the distinct ones).

The product of its (nonzero) digits is 762048, while the sum is 49.

The square root of 7947921640 is about 89151.1168746640. The cubic root of 7947921640 is about 1995.6506852534.

The spelling of 7947921640 in words is "seven billion, nine hundred forty-seven million, nine hundred twenty-one thousand, six hundred forty".