17666397225 has 27 divisors (see below), whose sum is σ = 31646051749. Its totient is φ = 9421015200.

The previous prime is 17666397173. The next prime is 17666397227. The reversal of 17666397225 is 52279366671.

The square root of 17666397225 is 132915.

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

It can be written as a sum of positive squares in 4 ways, for example, as 4626584361 + 13039812864 = 68019^2 + 114192^2 .

It is not a de Polignac number, because 17666397225 - 2¹⁷ = 17666266153 is a prime.

It is a super-2 number, since 2×17666397225² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (17666397227) 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, 1989295 + ... + 1998155.

Almost surely, 2^17666397225 is an apocalyptic number.

17666397225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

17666397225 is the 132915-th square number.

17666397225 is the 66458-th centered octagonal number.

It is an amenable number.

17666397225 is a deficient number, since it is larger than the sum of its proper divisors (13979654524).

17666397225 is an frugal number, since it uses more digits than its factorization.

17666397225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17738 (or 8869 counting only the distinct ones).

The product of its digits is 5715360, while the sum is 54.

The spelling of 17666397225 in words is "seventeen billion, six hundred sixty-six million, three hundred ninety-seven thousand, two hundred twenty-five".