666515525 has 12 divisors (see below), whose sum is σ = 890055012. Its totient is φ = 492195840.

The previous prime is 666515503. The next prime is 666515539. The reversal of 666515525 is 525515666.

666515525 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 6 ways, for example, as 10233601 + 656281924 = 3199^2 + 25618^2 .

It is not a de Polignac number, because 666515525 - 2¹⁰ = 666514501 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 11 ways as a sum of consecutive naturals, for example, 1025084 + ... + 1025733.

It is an arithmetic number, because the mean of its divisors is an integer number (74171251).

Almost surely, 2^666515525 is an apocalyptic number.

666515525 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

666515525 is a deficient number, since it is larger than the sum of its proper divisors (223539487).

666515525 is a wasteful number, since it uses less digits than its factorization.

666515525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2050840 (or 2050835 counting only the distinct ones).

The product of its digits is 270000, while the sum is 41.

The square root of 666515525 is about 25816.9619630196. The cubic root of 666515525 is about 873.5144425430.

The spelling of 666515525 in words is "six hundred sixty-six million, five hundred fifteen thousand, five hundred twenty-five".