666644525 has 6 divisors (see below), whose sum is σ = 826639242. Its totient is φ = 533315600.

The previous prime is 666644521. The next prime is 666644551. The reversal of 666644525 is 525446666.

It is a happy number.

666644525 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 3 ways, for example, as 41744521 + 624900004 = 6461^2 + 24998^2 .

It is not a de Polignac number, because 666644525 - 2² = 666644521 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666644521) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13332866 + ... + 13332915.

It is an arithmetic number, because the mean of its divisors is an integer number (137773207).

Almost surely, 2^666644525 is an apocalyptic number.

It is an amenable number.

666644525 is a deficient number, since it is larger than the sum of its proper divisors (159994717).

666644525 is a wasteful number, since it uses less digits than its factorization.

666644525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26665791 (or 26665786 counting only the distinct ones).

The product of its digits is 1036800, while the sum is 44.

The square root of 666644525 is about 25819.4601996246. The cubic root of 666644525 is about 873.5707933655.

The spelling of 666644525 in words is "six hundred sixty-six million, six hundred forty-four thousand, five hundred twenty-five".