679911781 has 2 divisors, whose sum is σ = 679911782. Its totient is φ = 679911780.

The previous prime is 679911769. The next prime is 679911863. The reversal of 679911781 is 187119976.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 675220225 + 4691556 = 25985^2 + 2166^2 .

It is a cyclic number.

It is not a de Polignac number, because 679911781 - 2¹³ = 679903589 is a prime.

It is a super-2 number, since 2×679911781² = 924560059885183922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (679911731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 339955890 + 339955891.

It is an arithmetic number, because the mean of its divisors is an integer number (339955891).

Almost surely, 2^679911781 is an apocalyptic number.

It is an amenable number.

679911781 is a deficient number, since it is larger than the sum of its proper divisors (1).

679911781 is an equidigital number, since it uses as much as digits as its factorization.

679911781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 190512, while the sum is 49.

The square root of 679911781 is about 26075.1180438364. The cubic root of 679911781 is about 879.3279049520.

The spelling of 679911781 in words is "six hundred seventy-nine million, nine hundred eleven thousand, seven hundred eighty-one".