20779916669 has 2 divisors, whose sum is σ = 20779916670. Its totient is φ = 20779916668.

The previous prime is 20779916593. The next prime is 20779916741. The reversal of 20779916669 is 96661997702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17652311044 + 3127605625 = 132862^2 + 55925^2 .

It is a cyclic number.

It is not a de Polignac number, because 20779916669 - 2¹⁶ = 20779851133 is a prime.

It is a super-2 number, since 2×20779916669² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20779916369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10389958334 + 10389958335.

It is an arithmetic number, because the mean of its divisors is an integer number (10389958335).

Almost surely, 2^20779916669 is an apocalyptic number.

It is an amenable number.

20779916669 is a deficient number, since it is larger than the sum of its proper divisors (1).

20779916669 is an equidigital number, since it uses as much as digits as its factorization.

20779916669 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15431472, while the sum is 62.

The spelling of 20779916669 in words is "twenty billion, seven hundred seventy-nine million, nine hundred sixteen thousand, six hundred sixty-nine".