209651141681 has 2 divisors, whose sum is σ = 209651141682. Its totient is φ = 209651141680.

The previous prime is 209651141671. The next prime is 209651141729. The reversal of 209651141681 is 186141156902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 187561751056 + 22089390625 = 433084^2 + 148625^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209651141681 is a prime.

It is a super-2 number, since 2×209651141681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (209651141671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104825570840 + 104825570841.

It is an arithmetic number, because the mean of its divisors is an integer number (104825570841).

Almost surely, 2^209651141681 is an apocalyptic number.

It is an amenable number.

209651141681 is a deficient number, since it is larger than the sum of its proper divisors (1).

209651141681 is an equidigital number, since it uses as much as digits as its factorization.

209651141681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 103680, while the sum is 44.

The spelling of 209651141681 in words is "two hundred nine billion, six hundred fifty-one million, one hundred forty-one thousand, six hundred eighty-one".