666215225 has 12 divisors (see below), whose sum is σ = 889653996. Its totient is φ = 491974080.

The previous prime is 666215219. The next prime is 666215257. The reversal of 666215225 is 522512666.

It can be written as a sum of positive squares in 6 ways, for example, as 2019241 + 664195984 = 1421^2 + 25772^2 .

It is not a de Polignac number, because 666215225 - 2⁶ = 666215161 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1024622 + ... + 1025271.

It is an arithmetic number, because the mean of its divisors is an integer number (74137833).

Almost surely, 2^666215225 is an apocalyptic number.

666215225 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

666215225 is a deficient number, since it is larger than the sum of its proper divisors (223438771).

666215225 is a wasteful number, since it uses less digits than its factorization.

666215225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2049916 (or 2049911 counting only the distinct ones).

The product of its digits is 43200, while the sum is 35.

The square root of 666215225 is about 25811.1453639702. The cubic root of 666215225 is about 873.3832349002.

The spelling of 666215225 in words is "six hundred sixty-six million, two hundred fifteen thousand, two hundred twenty-five".