6877921781 has 2 divisors, whose sum is σ = 6877921782. Its totient is φ = 6877921780.

The previous prime is 6877921759. The next prime is 6877921789. The reversal of 6877921781 is 1871297786.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5491551025 + 1386370756 = 74105^2 + 37234^2 .

It is a cyclic number.

It is not a de Polignac number, because 6877921781 - 2¹⁰ = 6877920757 is a prime.

It is a super-2 number, since 2×6877921781² = 94611616051108423922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6877921789) 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, 3438960890 + 3438960891.

It is an arithmetic number, because the mean of its divisors is an integer number (3438960891).

Almost surely, 2^6877921781 is an apocalyptic number.

It is an amenable number.

6877921781 is a deficient number, since it is larger than the sum of its proper divisors (1).

6877921781 is an equidigital number, since it uses as much as digits as its factorization.

6877921781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2370816, while the sum is 56.

The square root of 6877921781 is about 82933.2368896813. The cubic root of 6877921781 is about 1901.7455593638.

The spelling of 6877921781 in words is "six billion, eight hundred seventy-seven million, nine hundred twenty-one thousand, seven hundred eighty-one".