206507998681 has 2 divisors, whose sum is σ = 206507998682. Its totient is φ = 206507998680.

The previous prime is 206507998679. The next prime is 206507998693. The reversal of 206507998681 is 186899705602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 135706771456 + 70801227225 = 368384^2 + 266085^2 .

It is a cyclic number.

It is not a de Polignac number, because 206507998681 - 2¹ = 206507998679 is a prime.

It is a super-2 number, since 2×206507998681² (a number of 23 digits) contains 22 as substring.

Together with 206507998679, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (206507998381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103253999340 + 103253999341.

It is an arithmetic number, because the mean of its divisors is an integer number (103253999341).

Almost surely, 2^206507998681 is an apocalyptic number.

It is an amenable number.

206507998681 is a deficient number, since it is larger than the sum of its proper divisors (1).

206507998681 is an equidigital number, since it uses as much as digits as its factorization.

206507998681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13063680, while the sum is 61.

The spelling of 206507998681 in words is "two hundred six billion, five hundred seven million, nine hundred ninety-eight thousand, six hundred eighty-one".