6921390247 has 2 divisors, whose sum is σ = 6921390248. Its totient is φ = 6921390246.

The previous prime is 6921390239. The next prime is 6921390263. The reversal of 6921390247 is 7420931296.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6921390247 - 2³ = 6921390239 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6921393247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3460695123 + 3460695124.

It is an arithmetic number, because the mean of its divisors is an integer number (3460695124).

Almost surely, 2^6921390247 is an apocalyptic number.

6921390247 is a deficient number, since it is larger than the sum of its proper divisors (1).

6921390247 is an equidigital number, since it uses as much as digits as its factorization.

6921390247 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 163296, while the sum is 43.

The square root of 6921390247 is about 83194.8931545681. The cubic root of 6921390247 is about 1905.7434928520.

The spelling of 6921390247 in words is "six billion, nine hundred twenty-one million, three hundred ninety thousand, two hundred forty-seven".