666631525 has 36 divisors (see below), whose sum is σ = 964294308. Its totient is φ = 455831040.

The previous prime is 666631519. The next prime is 666631541. The reversal of 666631525 is 525136666.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 9529569 + 657101956 = 3087^2 + 25634^2 .

It is not a de Polignac number, because 666631525 - 2¹³ = 666623333 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 681837 + ... + 682813.

It is an arithmetic number, because the mean of its divisors is an integer number (26785953).

Almost surely, 2^666631525 is an apocalyptic number.

It is an amenable number.

666631525 is a deficient number, since it is larger than the sum of its proper divisors (297662783).

666631525 is a wasteful number, since it uses less digits than its factorization.

666631525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1558 (or 1546 counting only the distinct ones).

The product of its digits is 194400, while the sum is 40.

The square root of 666631525 is about 25819.2084502992. The cubic root of 666631525 is about 873.5651149298.

The spelling of 666631525 in words is "six hundred sixty-six million, six hundred thirty-one thousand, five hundred twenty-five".