206801864921 has 2 divisors, whose sum is σ = 206801864922. Its totient is φ = 206801864920.

The previous prime is 206801864903. The next prime is 206801864953. The reversal of 206801864921 is 129468108602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 157342328896 + 49459536025 = 396664^2 + 222395^2 .

It is a cyclic number.

It is not a de Polignac number, because 206801864921 - 2¹⁰ = 206801863897 is a prime.

It is a super-2 number, since 2×206801864921² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (206801864981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103400932460 + 103400932461.

It is an arithmetic number, because the mean of its divisors is an integer number (103400932461).

Almost surely, 2^206801864921 is an apocalyptic number.

It is an amenable number.

206801864921 is a deficient number, since it is larger than the sum of its proper divisors (1).

206801864921 is an equidigital number, since it uses as much as digits as its factorization.

206801864921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 331776, while the sum is 47.

The spelling of 206801864921 in words is "two hundred six billion, eight hundred one million, eight hundred sixty-four thousand, nine hundred twenty-one".