209777740225 has 27 divisors (see below), whose sum is σ = 265913151817. Its totient is φ = 164167232480.

The previous prime is 209777740223. The next prime is 209777740259. The reversal of 209777740225 is 522047777902.

The square root of 209777740225 is 458015.

It is a perfect power (a square), and thus also a powerful number.

209777740225 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 7212935041 + 202564805184 = 84929^2 + 450072^2 .

It is not a de Polignac number, because 209777740225 - 2¹ = 209777740223 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209777740223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 107632551 + ... + 107634499.

Almost surely, 2^209777740225 is an apocalyptic number.

209777740225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

209777740225 is the 458015-th square number.

209777740225 is the 229008-th centered octagonal number.

It is an amenable number.

209777740225 is a deficient number, since it is larger than the sum of its proper divisors (56135411592).

209777740225 is an frugal number, since it uses more digits than its factorization.

209777740225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4002 (or 2001 counting only the distinct ones).

The product of its (nonzero) digits is 3457440, while the sum is 52.

The spelling of 209777740225 in words is "two hundred nine billion, seven hundred seventy-seven million, seven hundred forty thousand, two hundred twenty-five".