1261275757 has 4 divisors (see below), whose sum is σ = 1441458016. Its totient is φ = 1081093500.

The previous prime is 1261275751. The next prime is 1261275773. The reversal of 1261275757 is 7575721621.

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 1261275757 - 2¹⁹ = 1260751469 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 (1261275751) 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, 90091119 + ... + 90091132.

It is an arithmetic number, because the mean of its divisors is an integer number (360364504).

Almost surely, 2^1261275757 is an apocalyptic number.

It is an amenable number.

1261275757 is a deficient number, since it is larger than the sum of its proper divisors (180182259).

1261275757 is an equidigital number, since it uses as much as digits as its factorization.

1261275757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180182258.

The product of its digits is 205800, while the sum is 43.

The square root of 1261275757 is about 35514.4443431120. Note that the first 3 decimals coincide. The cubic root of 1261275757 is about 1080.4467050708.

The spelling of 1261275757 in words is "one billion, two hundred sixty-one million, two hundred seventy-five thousand, seven hundred fifty-seven".