6709917821 has 2 divisors, whose sum is σ = 6709917822. Its totient is φ = 6709917820.

The previous prime is 6709917793. The next prime is 6709917871. The reversal of 6709917821 is 1287199076.

It is an a-pointer prime, because the next prime (6709917871) can be obtained adding 6709917821 to its sum of digits (50).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6158325625 + 551592196 = 78475^2 + 23486^2 .

It is a cyclic number.

It is not a de Polignac number, because 6709917821 - 2¹⁰ = 6709916797 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6709917821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6709917871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3354958910 + 3354958911.

It is an arithmetic number, because the mean of its divisors is an integer number (3354958911).

Almost surely, 2^6709917821 is an apocalyptic number.

It is an amenable number.

6709917821 is a deficient number, since it is larger than the sum of its proper divisors (1).

6709917821 is an equidigital number, since it uses as much as digits as its factorization.

6709917821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 381024, while the sum is 50.

The square root of 6709917821 is about 81914.0880496145. The cubic root of 6709917821 is about 1886.1333769980.

The spelling of 6709917821 in words is "six billion, seven hundred nine million, nine hundred seventeen thousand, eight hundred twenty-one".