206666455256623 has 4 divisors (see below), whose sum is σ = 206988867823968. Its totient is φ = 206344042689280.

The previous prime is 206666455256567. The next prime is 206666455256713. The reversal of 206666455256623 is 326652554666602.

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

It is a cyclic number.

It is not a de Polignac number, because 206666455256623 - 2¹³ = 206666455248431 is a prime.

It is a super-5 number, since 5×206666455256623⁵ (a number of 73 digits) contains 55555 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206666455256123) 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, 161206282711 + ... + 161206283992.

It is an arithmetic number, because the mean of its divisors is an integer number (51747216955992).

Almost surely, 2^{206666455256623} is an apocalyptic number.

206666455256623 is a deficient number, since it is larger than the sum of its proper divisors (322412567345).

206666455256623 is an equidigital number, since it uses as much as digits as its factorization.

206666455256623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322412567344.

The product of its (nonzero) digits is 559872000, while the sum is 64.

The spelling of 206666455256623 in words is "two hundred six trillion, six hundred sixty-six billion, four hundred fifty-five million, two hundred fifty-six thousand, six hundred twenty-three".