206606921 has 2 divisors, whose sum is σ = 206606922. Its totient is φ = 206606920.

The previous prime is 206606891. The next prime is 206606957. The reversal of 206606921 is 129606602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 205606921 + 1000000 = 14339^2 + 1000^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-206606921 is a prime.

It is a super-3 number, since 3×206606921³ (a number of 26 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (206603921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103303460 + 103303461.

It is an arithmetic number, because the mean of its divisors is an integer number (103303461).

Almost surely, 2^206606921 is an apocalyptic number.

It is an amenable number.

206606921 is a deficient number, since it is larger than the sum of its proper divisors (1).

206606921 is an equidigital number, since it uses as much as digits as its factorization.

206606921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 206606921 is about 14373.8276391503. The cubic root of 206606921 is about 591.1734960542.

The spelling of 206606921 in words is "two hundred six million, six hundred six thousand, nine hundred twenty-one".