1276145561 has 2 divisors, whose sum is σ = 1276145562. Its totient is φ = 1276145560.

The previous prime is 1276145531. The next prime is 1276145569. The reversal of 1276145561 is 1655416721.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 863243161 + 412902400 = 29381^2 + 20320^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1276145561 is a prime.

It is not a weakly prime, because it can be changed into another prime (1276145569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 638072780 + 638072781.

It is an arithmetic number, because the mean of its divisors is an integer number (638072781).

Almost surely, 2^1276145561 is an apocalyptic number.

It is an amenable number.

1276145561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1276145561 is an equidigital number, since it uses as much as digits as its factorization.

1276145561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 50400, while the sum is 38.

The square root of 1276145561 is about 35723.1796037251. The cubic root of 1276145561 is about 1084.6761011561.

The spelling of 1276145561 in words is "one billion, two hundred seventy-six million, one hundred forty-five thousand, five hundred sixty-one".