7868686521 has 24 divisors (see below), whose sum is σ = 11327818624. Its totient is φ = 4856244480.

The previous prime is 7868686519. The next prime is 7868686523. The reversal of 7868686521 is 1256868687.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (7868686519) and next prime (7868686523).

It is not a de Polignac number, because 7868686521 - 2¹ = 7868686519 is a prime.

It is a Smith number, since the sum of its digits (57) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (7868686523) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21505 + ... + 127278.

Almost surely, 2^7868686521 is an apocalyptic number.

It is an amenable number.

7868686521 is a deficient number, since it is larger than the sum of its proper divisors (3459132103).

7868686521 is a wasteful number, since it uses less digits than its factorization.

7868686521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148881 (or 148864 counting only the distinct ones).

The product of its digits is 7741440, while the sum is 57.

The square root of 7868686521 is about 88705.6171896684. The cubic root of 7868686521 is about 1988.9967857352.

The spelling of 7868686521 in words is "seven billion, eight hundred sixty-eight million, six hundred eighty-six thousand, five hundred twenty-one".