7857691451921 has 4 divisors (see below), whose sum is σ = 7857762556644. Its totient is φ = 7857620347200.

The previous prime is 7857691451873. The next prime is 7857691451941. The reversal of 7857691451921 is 1291541967587.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2395019332225 + 5462672119696 = 1547585^2 + 2337236^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7857691451921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7857691451941) 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 3 ways as a sum of consecutive naturals, for example, 35386340 + ... + 35607701.

It is an arithmetic number, because the mean of its divisors is an integer number (1964440639161).

Almost surely, 2^{7857691451921} is an apocalyptic number.

It is an amenable number.

7857691451921 is a deficient number, since it is larger than the sum of its proper divisors (71104723).

7857691451921 is a wasteful number, since it uses less digits than its factorization.

7857691451921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71104722.

The product of its digits is 38102400, while the sum is 65.

The spelling of 7857691451921 in words is "seven trillion, eight hundred fifty-seven billion, six hundred ninety-one million, four hundred fifty-one thousand, nine hundred twenty-one".