7857689166649 has 81 divisors (see below), whose sum is σ = 9584674478253. Its totient is φ = 6422952122496.

The previous prime is 7857689166631. The next prime is 7857689166671. The reversal of 7857689166649 is 9466619867587.

The square root of 7857689166649 is 2803157.

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

It can be written as a sum of positive squares in 4 ways, for example, as 2097593166249 + 5760096000400 = 1448307^2 + 2400020^2 .

It is not a de Polignac number, because 7857689166649 - 2¹⁷ = 7857689035577 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7857689166149) 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 80 ways as a sum of consecutive naturals, for example, 57355395309 + ... + 57355395445.

Almost surely, 2^{7857689166649} is an apocalyptic number.

7857689166649 is a gapful number since it is divisible by the number (79) formed by its first and last digit.

7857689166649 is the 2803157-th square number.

7857689166649 is the 1401579-th centered octagonal number.

It is an amenable number.

7857689166649 is a deficient number, since it is larger than the sum of its proper divisors (1726985311604).

7857689166649 is an frugal number, since it uses more digits than its factorization.

7857689166649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 520 (or 260 counting only the distinct ones).

The product of its digits is 6584094720, while the sum is 82.

The spelling of 7857689166649 in words is "seven trillion, eight hundred fifty-seven billion, six hundred eighty-nine million, one hundred sixty-six thousand, six hundred forty-nine".