206106721 has 4 divisors (see below), whose sum is σ = 206145792. Its totient is φ = 206067652.

The previous prime is 206106707. The next prime is 206106757. The reversal of 206106721 is 127601602.

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, and also an emirpimes, since its reverse is a distinct semiprime: 127601602 = 2 ⋅63800801.

It is a cyclic number.

It is not a de Polignac number, because 206106721 - 2⁹ = 206106209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (206107721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10105 + ... + 22678.

It is an arithmetic number, because the mean of its divisors is an integer number (51536448).

Almost surely, 2^206106721 is an apocalyptic number.

It is an amenable number.

206106721 is a deficient number, since it is larger than the sum of its proper divisors (39071).

206106721 is an equidigital number, since it uses as much as digits as its factorization.

206106721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39070.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 206106721 is about 14356.4174152189. The cubic root of 206106721 is about 590.6960290863.

The spelling of 206106721 in words is "two hundred six million, one hundred six thousand, seven hundred twenty-one".