6646977749 has 4 divisors (see below), whose sum is σ = 6663721164. Its totient is φ = 6630234336.

The previous prime is 6646977677. The next prime is 6646977751. The reversal of 6646977749 is 9477796466.

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 2471879524 + 4175098225 = 49718^2 + 64615^2 .

It is a cyclic number.

It is not a de Polignac number, because 6646977749 - 2²⁸ = 6378542293 is a prime.

It is a super-2 number, since 2×6646977749² = 88364626391402214002, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6646977149) 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, 8371112 + ... + 8371905.

It is an arithmetic number, because the mean of its divisors is an integer number (1665930291).

Almost surely, 2^6646977749 is an apocalyptic number.

It is an amenable number.

6646977749 is a deficient number, since it is larger than the sum of its proper divisors (16743415).

6646977749 is a wasteful number, since it uses less digits than its factorization.

6646977749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16743414.

The product of its digits is 96018048, while the sum is 65.

The square root of 6646977749 is about 81528.9994357836. Note that the first 3 decimals coincide. The cubic root of 6646977749 is about 1880.2174326946.

The spelling of 6646977749 in words is "six billion, six hundred forty-six million, nine hundred seventy-seven thousand, seven hundred forty-nine".