6921349821 has 6 divisors (see below), whose sum is σ = 9997505310. Its totient is φ = 4614233208.

The previous prime is 6921349807. The next prime is 6921349837. The reversal of 6921349821 is 1289431296.

It can be written as a sum of positive squares in only one way, i.e., 6787947321 + 133402500 = 82389^2 + 11550^2 .

It is not a de Polignac number, because 6921349821 - 2⁷ = 6921349693 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6921349021) 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 5 ways as a sum of consecutive naturals, for example, 384519426 + ... + 384519443.

It is an arithmetic number, because the mean of its divisors is an integer number (1666250885).

Almost surely, 2^6921349821 is an apocalyptic number.

It is an amenable number.

6921349821 is a deficient number, since it is larger than the sum of its proper divisors (3076155489).

6921349821 is a wasteful number, since it uses less digits than its factorization.

6921349821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 769038875 (or 769038872 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 6921349821 is about 83194.6501945888. The cubic root of 6921349821 is about 1905.7397825311.

The spelling of 6921349821 in words is "six billion, nine hundred twenty-one million, three hundred forty-nine thousand, eight hundred twenty-one".