666250261 has 4 divisors (see below), whose sum is σ = 666319500. Its totient is φ = 666181024.

The previous prime is 666250253. The next prime is 666250267. The reversal of 666250261 is 162052666.

666250261 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 162052666 = 2 ⋅81026333.

It can be written as a sum of positive squares in 2 ways, for example, as 402804900 + 263445361 = 20070^2 + 16231^2 .

It is a cyclic number.

It is not a de Polignac number, because 666250261 - 2³ = 666250253 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 (666250267) 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, 17296 + ... + 40393.

It is an arithmetic number, because the mean of its divisors is an integer number (166579875).

Almost surely, 2^666250261 is an apocalyptic number.

It is an amenable number.

666250261 is a deficient number, since it is larger than the sum of its proper divisors (69239).

666250261 is a wasteful number, since it uses less digits than its factorization.

666250261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69238.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 666250261 is about 25811.8240541036. The cubic root of 666250261 is about 873.3985449269.

The spelling of 666250261 in words is "six hundred sixty-six million, two hundred fifty thousand, two hundred sixty-one".