209820977864669 has 2 divisors, whose sum is σ = 209820977864670. Its totient is φ = 209820977864668.

The previous prime is 209820977864653. The next prime is 209820977864683. The reversal of 209820977864669 is 966468779028902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 121394450947225 + 88426526917444 = 11017915^2 + 9403538^2 .

It is a cyclic number.

It is not a de Polignac number, because 209820977864669 - 2⁴ = 209820977864653 is a prime.

It is a super-2 number, since 2×209820977864669² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209820977864639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104910488932334 + 104910488932335.

It is an arithmetic number, because the mean of its divisors is an integer number (104910488932335).

Almost surely, 2^{209820977864669} is an apocalyptic number.

It is an amenable number.

209820977864669 is a deficient number, since it is larger than the sum of its proper divisors (1).

209820977864669 is an equidigital number, since it uses as much as digits as its factorization.

209820977864669 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7900913664, while the sum is 83.

The spelling of 209820977864669 in words is "two hundred nine trillion, eight hundred twenty billion, nine hundred seventy-seven million, eight hundred sixty-four thousand, six hundred sixty-nine".