861279779 has 2 divisors, whose sum is σ = 861279780. Its totient is φ = 861279778.

The previous prime is 861279773. The next prime is 861279829. The reversal of 861279779 is 977972168.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 861279779 - 2¹² = 861275683 is a prime.

It is not a weakly prime, because it can be changed into another prime (861279773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430639889 + 430639890.

It is an arithmetic number, because the mean of its divisors is an integer number (430639890).

Almost surely, 2^861279779 is an apocalyptic number.

861279779 is a deficient number, since it is larger than the sum of its proper divisors (1).

861279779 is an equidigital number, since it uses as much as digits as its factorization.

861279779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2667168, while the sum is 56.

The square root of 861279779 is about 29347.5685364222. The cubic root of 861279779 is about 951.4400243965.

The spelling of 861279779 in words is "eight hundred sixty-one million, two hundred seventy-nine thousand, seven hundred seventy-nine".