666387605 has 8 divisors (see below), whose sum is σ = 861177912. Its totient is φ = 492101568.

The previous prime is 666387593. The next prime is 666387643. The reversal of 666387605 is 506783666.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 13942756 + 652444849 = 3734^2 + 25543^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 666387605 - 2²⁰ = 665339029 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 666387605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5125994 + ... + 5126123.

It is an arithmetic number, because the mean of its divisors is an integer number (107647239).

Almost surely, 2^666387605 is an apocalyptic number.

666387605 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

666387605 is a deficient number, since it is larger than the sum of its proper divisors (194790307).

666387605 is a wasteful number, since it uses less digits than its factorization.

666387605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10252135.

The product of its (nonzero) digits is 1088640, while the sum is 47.

The square root of 666387605 is about 25814.4844031408. The cubic root of 666387605 is about 873.4585563145.

The spelling of 666387605 in words is "six hundred sixty-six million, three hundred eighty-seven thousand, six hundred five".