6778871621 has 2 divisors, whose sum is σ = 6778871622. Its totient is φ = 6778871620.

The previous prime is 6778871609. The next prime is 6778871677. The reversal of 6778871621 is 1261788776.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4982383396 + 1796488225 = 70586^2 + 42385^2 .

It is a cyclic number.

It is not a de Polignac number, because 6778871621 - 2¹⁸ = 6778609477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6778871821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3389435810 + 3389435811.

It is an arithmetic number, because the mean of its divisors is an integer number (3389435811).

Almost surely, 2^6778871621 is an apocalyptic number.

It is an amenable number.

6778871621 is a deficient number, since it is larger than the sum of its proper divisors (1).

6778871621 is an equidigital number, since it uses as much as digits as its factorization.

6778871621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1580544, while the sum is 53.

The square root of 6778871621 is about 82333.9032294716. The cubic root of 6778871621 is about 1892.5722579960.

The spelling of 6778871621 in words is "six billion, seven hundred seventy-eight million, eight hundred seventy-one thousand, six hundred twenty-one".