668042261 has 4 divisors (see below), whose sum is σ = 703202400. Its totient is φ = 632882124.

The previous prime is 668042239. The next prime is 668042269. The reversal of 668042261 is 162240866.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 162240866 = 2 ⋅81120433.

It is a cyclic number.

It is not a de Polignac number, because 668042261 - 2⁶ = 668042197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668042269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17580041 + ... + 17580078.

It is an arithmetic number, because the mean of its divisors is an integer number (175800600).

Almost surely, 2^668042261 is an apocalyptic number.

It is an amenable number.

668042261 is a deficient number, since it is larger than the sum of its proper divisors (35160139).

668042261 is a wasteful number, since it uses less digits than its factorization.

668042261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35160138.

The product of its (nonzero) digits is 27648, while the sum is 35.

The square root of 668042261 is about 25846.5135173005. The cubic root of 668042261 is about 874.1808981176.

The spelling of 668042261 in words is "six hundred sixty-eight million, forty-two thousand, two hundred sixty-one".