6861664261 has 2 divisors, whose sum is σ = 6861664262. Its totient is φ = 6861664260.

The previous prime is 6861664259. The next prime is 6861664297. The reversal of 6861664261 is 1624661686.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5222952900 + 1638711361 = 72270^2 + 40481^2 .

It is a cyclic number.

It is not a de Polignac number, because 6861664261 - 2¹ = 6861664259 is a prime.

It is a super-2 number, since 2×6861664261² = 94164872861369352242, which contains 22 as substring.

Together with 6861664259, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6861604261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3430832130 + 3430832131.

It is an arithmetic number, because the mean of its divisors is an integer number (3430832131).

Almost surely, 2^6861664261 is an apocalyptic number.

It is an amenable number.

6861664261 is a deficient number, since it is larger than the sum of its proper divisors (1).

6861664261 is an equidigital number, since it uses as much as digits as its factorization.

6861664261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 497664, while the sum is 46.

The square root of 6861664261 is about 82835.1631917267. The cubic root of 6861664261 is about 1900.2459756336.

The spelling of 6861664261 in words is "six billion, eight hundred sixty-one million, six hundred sixty-four thousand, two hundred sixty-one".