6688670521 has 4 divisors (see below), whose sum is σ = 7203183652. Its totient is φ = 6174157392.

The previous prime is 6688670507. The next prime is 6688670537. The reversal of 6688670521 is 1250768866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1250768866 = 2 ⋅625384433.

It can be written as a sum of positive squares in 2 ways, for example, as 1723495225 + 4965175296 = 41515^2 + 70464^2 .

It is not a de Polignac number, because 6688670521 - 2⁷ = 6688670393 is a prime.

It is a super-2 number, since 2×6688670521² = 89476626676988822882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6688670551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 257256546 + ... + 257256571.

It is an arithmetic number, because the mean of its divisors is an integer number (1800795913).

Almost surely, 2^6688670521 is an apocalyptic number.

It is an amenable number.

6688670521 is a deficient number, since it is larger than the sum of its proper divisors (514513131).

6688670521 is a wasteful number, since it uses less digits than its factorization.

6688670521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 514513130.

The product of its (nonzero) digits is 967680, while the sum is 49.

The square root of 6688670521 is about 81784.2926300644. The cubic root of 6688670521 is about 1884.1404257951.

The spelling of 6688670521 in words is "six billion, six hundred eighty-eight million, six hundred seventy thousand, five hundred twenty-one".