666212765 has 8 divisors (see below), whose sum is σ = 800434008. Its totient is φ = 532317760.

The previous prime is 666212759. The next prime is 666212783. The reversal of 666212765 is 567212666.

It can be written as a sum of positive squares in 4 ways, for example, as 36554116 + 629658649 = 6046^2 + 25093^2 .

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

It is not a de Polignac number, because 666212765 - 2⁴ = 666212749 is a prime.

It is a Duffinian number.

It is a Curzon number.

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, 77042 + ... + 85251.

It is an arithmetic number, because the mean of its divisors is an integer number (100054251).

Almost surely, 2^666212765 is an apocalyptic number.

It is an amenable number.

666212765 is a deficient number, since it is larger than the sum of its proper divisors (134221243).

666212765 is a wasteful number, since it uses less digits than its factorization.

666212765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163119.

The product of its digits is 181440, while the sum is 41.

The square root of 666212765 is about 25811.0977100936. The cubic root of 666212765 is about 873.3821599096.

Subtracting from 666212765 its reverse (567212666), we obtain a palindrome (99000099).

The spelling of 666212765 in words is "six hundred sixty-six million, two hundred twelve thousand, seven hundred sixty-five".