206916577921 has 2 divisors, whose sum is σ = 206916577922. Its totient is φ = 206916577920.

The previous prime is 206916577897. The next prime is 206916577943. The reversal of 206916577921 is 129775619602.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 125129157696 + 81787420225 = 353736^2 + 285985^2 .

It is a cyclic number.

It is not a de Polignac number, because 206916577921 - 2²⁷ = 206782360193 is a prime.

It is not a weakly prime, because it can be changed into another prime (206916577421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103458288960 + 103458288961.

It is an arithmetic number, because the mean of its divisors is an integer number (103458288961).

Almost surely, 2^206916577921 is an apocalyptic number.

It is an amenable number.

206916577921 is a deficient number, since it is larger than the sum of its proper divisors (1).

206916577921 is an equidigital number, since it uses as much as digits as its factorization.

206916577921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2857680, while the sum is 55.

The spelling of 206916577921 in words is "two hundred six billion, nine hundred sixteen million, five hundred seventy-seven thousand, nine hundred twenty-one".