6821640253 has 2 divisors, whose sum is σ = 6821640254. Its totient is φ = 6821640252.

The previous prime is 6821640233. The next prime is 6821640257. The reversal of 6821640253 is 3520461286.

6821640253 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5167021924 + 1654618329 = 71882^2 + 40677^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6821640253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6821640257) 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 as a sum of consecutive naturals, namely, 3410820126 + 3410820127.

It is an arithmetic number, because the mean of its divisors is an integer number (3410820127).

Almost surely, 2^6821640253 is an apocalyptic number.

It is an amenable number.

6821640253 is a deficient number, since it is larger than the sum of its proper divisors (1).

6821640253 is an equidigital number, since it uses as much as digits as its factorization.

6821640253 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69120, while the sum is 37.

The square root of 6821640253 is about 82593.2215923317. The cubic root of 6821640253 is about 1896.5440643005.

The spelling of 6821640253 in words is "six billion, eight hundred twenty-one million, six hundred forty thousand, two hundred fifty-three".