206666171381 has 4 divisors (see below), whose sum is σ = 207114471564. Its totient is φ = 206217871200.

The previous prime is 206666171377. The next prime is 206666171449. The reversal of 206666171381 is 183171666602.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 89739788356 + 116926383025 = 299566^2 + 341945^2 .

It is a cyclic number.

It is not a de Polignac number, because 206666171381 - 2² = 206666171377 is a prime.

It is a super-2 number, since 2×206666171381² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206666171311) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 224149400 + ... + 224150321.

It is an arithmetic number, because the mean of its divisors is an integer number (51778617891).

Almost surely, 2^206666171381 is an apocalyptic number.

It is an amenable number.

206666171381 is a deficient number, since it is larger than the sum of its proper divisors (448300183).

206666171381 is an equidigital number, since it uses as much as digits as its factorization.

206666171381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 448300182.

The product of its (nonzero) digits is 435456, while the sum is 47.

The spelling of 206666171381 in words is "two hundred six billion, six hundred sixty-six million, one hundred seventy-one thousand, three hundred eighty-one".