6821426665 has 4 divisors (see below), whose sum is σ = 8185712004. Its totient is φ = 5457141328.

The previous prime is 6821426621. The next prime is 6821426669. The reversal of 6821426665 is 5666241286.

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 4996086489 + 1825340176 = 70683^2 + 42724^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6821426665 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6821426669) 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 3 ways as a sum of consecutive naturals, for example, 682142662 + ... + 682142671.

It is an arithmetic number, because the mean of its divisors is an integer number (2046428001).

Almost surely, 2^6821426665 is an apocalyptic number.

It is an amenable number.

6821426665 is a deficient number, since it is larger than the sum of its proper divisors (1364285339).

6821426665 is a wasteful number, since it uses less digits than its factorization.

6821426665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1364285338.

The product of its digits is 829440, while the sum is 46.

The square root of 6821426665 is about 82591.9285705328. The cubic root of 6821426665 is about 1896.5242702692.

The spelling of 6821426665 in words is "six billion, eight hundred twenty-one million, four hundred twenty-six thousand, six hundred sixty-five".