66185280225 has 45 divisors (see below), whose sum is σ = 122619466057. Its totient is φ = 35292641760.

The previous prime is 66185280211. The next prime is 66185280307. The reversal of 66185280225 is 52208258166.

It is a happy number.

The square root of 66185280225 is 257265.

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

66185280225 is a `hidden beast` number, since 6 + 618 + 5 + 2 + 8 + 0 + 2 + 25 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 226713249 + 65958566976 = 15057^2 + 256824^2 .

It is a tau number, because it is divible by the number of its divisors (45).

It is not a de Polignac number, because 66185280225 - 2¹³ = 66185272033 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 11574067 + ... + 11579783.

Almost surely, 2^66185280225 is an apocalyptic number.

66185280225 is the 257265-th square number.

66185280225 is the 128633-rd centered octagonal number.

It is an amenable number.

66185280225 is a deficient number, since it is larger than the sum of its proper divisors (56434185832).

66185280225 is an frugal number, since it uses more digits than its factorization.

66185280225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11456 (or 5725 counting only the distinct ones).

The product of its (nonzero) digits is 460800, while the sum is 45.

The spelling of 66185280225 in words is "sixty-six billion, one hundred eighty-five million, two hundred eighty thousand, two hundred twenty-five".