206722561 has 4 divisors (see below), whose sum is σ = 207649792. Its totient is φ = 205795332.

The previous prime is 206722507. The next prime is 206722573. The reversal of 206722561 is 165227602.

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 not a de Polignac number, because 206722561 - 2⁷ = 206722433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (206722501) 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, 463281 + ... + 463726.

It is an arithmetic number, because the mean of its divisors is an integer number (51912448).

Almost surely, 2^206722561 is an apocalyptic number.

It is an amenable number.

206722561 is a deficient number, since it is larger than the sum of its proper divisors (927231).

206722561 is an equidigital number, since it uses as much as digits as its factorization.

206722561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 927230.

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 206722561 is about 14377.8496653707. The cubic root of 206722561 is about 591.2837707603.

The spelling of 206722561 in words is "two hundred six million, seven hundred twenty-two thousand, five hundred sixty-one".