1210666261 has 4 divisors (see below), whose sum is σ = 1383618592. Its totient is φ = 1037713932.

The previous prime is 1210666243. The next prime is 1210666267. The reversal of 1210666261 is 1626660121.

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: 1626660121 = 1811 ⋅898211.

It is a cyclic number.

It is not a de Polignac number, because 1210666261 - 2⁷ = 1210666133 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 (1210666267) 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, 86476155 + ... + 86476168.

It is an arithmetic number, because the mean of its divisors is an integer number (345904648).

Almost surely, 2^1210666261 is an apocalyptic number.

It is an amenable number.

1210666261 is a deficient number, since it is larger than the sum of its proper divisors (172952331).

1210666261 is an equidigital number, since it uses as much as digits as its factorization.

1210666261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172952330.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 1210666261 is about 34794.6297724232. The cubic root of 1210666261 is about 1065.7977846845.

The spelling of 1210666261 in words is "one billion, two hundred ten million, six hundred sixty-six thousand, two hundred sixty-one".