1261280249 has 4 divisors (see below), whose sum is σ = 1327663440. Its totient is φ = 1194897060.

The previous prime is 1261280239. The next prime is 1261280261. The reversal of 1261280249 is 9420821621.

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 1261280249 - 2²⁰ = 1260231673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1261280239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33191567 + ... + 33191604.

It is an arithmetic number, because the mean of its divisors is an integer number (331915860).

Almost surely, 2^1261280249 is an apocalyptic number.

1261280249 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1261280249 is a deficient number, since it is larger than the sum of its proper divisors (66383191).

1261280249 is an equidigital number, since it uses as much as digits as its factorization.

1261280249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66383190.

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 1261280249 is about 35514.5075849293. The cubic root of 1261280249 is about 1080.4479877300.

The spelling of 1261280249 in words is "one billion, two hundred sixty-one million, two hundred eighty thousand, two hundred forty-nine".