1261266649 has 4 divisors (see below), whose sum is σ = 1279031040. Its totient is φ = 1243502260.

The previous prime is 1261266631. The next prime is 1261266661. The reversal of 1261266649 is 9466621621.

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.

It is a cyclic number.

It is not a de Polignac number, because 1261266649 - 2⁹ = 1261266137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1261266749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8882089 + ... + 8882230.

It is an arithmetic number, because the mean of its divisors is an integer number (319757760).

Almost surely, 2^1261266649 is an apocalyptic number.

It is an amenable number.

1261266649 is a deficient number, since it is larger than the sum of its proper divisors (17764391).

1261266649 is an equidigital number, since it uses as much as digits as its factorization.

1261266649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17764390.

The product of its digits is 186624, while the sum is 43.

The square root of 1261266649 is about 35514.3161133648. The cubic root of 1261266649 is about 1080.4441043357. Note that the first 3 decimals are identical.

The spelling of 1261266649 in words is "one billion, two hundred sixty-one million, two hundred sixty-six thousand, six hundred forty-nine".