666915071 has 4 divisors (see below), whose sum is σ = 666988752. Its totient is φ = 666841392.

The previous prime is 666915031. The next prime is 666915089. The reversal of 666915071 is 170519666.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 666915071 - 2¹⁸ = 666652927 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 (666915031) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20990 + ... + 42123.

It is an arithmetic number, because the mean of its divisors is an integer number (166747188).

Almost surely, 2^666915071 is an apocalyptic number.

666915071 is a deficient number, since it is larger than the sum of its proper divisors (73681).

666915071 is a wasteful number, since it uses less digits than its factorization.

666915071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73680.

The product of its (nonzero) digits is 68040, while the sum is 41.

The square root of 666915071 is about 25824.6988559402. The cubic root of 666915071 is about 873.6889518496.

The spelling of 666915071 in words is "six hundred sixty-six million, nine hundred fifteen thousand, seventy-one".