209841867225 has 27 divisors (see below), whose sum is σ = 375862407583. Its totient is φ = 111911997840.

The previous prime is 209841867223. The next prime is 209841867239. The reversal of 209841867225 is 522768148902.

The square root of 209841867225 is 458085.

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

It can be written as a sum of positive squares in only one way, i.e., 75543072201 + 134298795024 = 274851^2 + 366468^2 .

It is not a de Polignac number, because 209841867225 - 2¹ = 209841867223 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209841867223) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 6856006 + ... + 6886544.

Almost surely, 2^209841867225 is an apocalyptic number.

209841867225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

209841867225 is the 458085-th square number.

209841867225 is the 229043-rd centered octagonal number.

It is an amenable number.

209841867225 is a deficient number, since it is larger than the sum of its proper divisors (166020540358).

209841867225 is an frugal number, since it uses more digits than its factorization.

209841867225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61094 (or 30547 counting only the distinct ones).

The product of its (nonzero) digits is 3870720, while the sum is 54.

The spelling of 209841867225 in words is "two hundred nine billion, eight hundred forty-one million, eight hundred sixty-seven thousand, two hundred twenty-five".