206121551205217 has 4 divisors (see below), whose sum is σ = 206121587164416. Its totient is φ = 206121515246020.

The previous prime is 206121551205187. The next prime is 206121551205239. The reversal of 206121551205217 is 712502155121602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-206121551205217 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 206121551205217.

It is not an unprimeable number, because it can be changed into a prime (206121551206217) 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, 7245193 + ... + 21557734.

It is an arithmetic number, because the mean of its divisors is an integer number (51530396791104).

Almost surely, 2^{206121551205217} is an apocalyptic number.

It is an amenable number.

206121551205217 is a deficient number, since it is larger than the sum of its proper divisors (35959199).

206121551205217 is an equidigital number, since it uses as much as digits as its factorization.

206121551205217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35959198.

The product of its (nonzero) digits is 84000, while the sum is 40.

The spelling of 206121551205217 in words is "two hundred six trillion, one hundred twenty-one billion, five hundred fifty-one million, two hundred five thousand, two hundred seventeen".