1256131909 has 2 divisors, whose sum is σ = 1256131910. Its totient is φ = 1256131908.

The previous prime is 1256131859. The next prime is 1256131931. The reversal of 1256131909 is 9091316521.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 948024100 + 308107809 = 30790^2 + 17553^2 .

It is a cyclic number.

It is not a de Polignac number, because 1256131909 - 2⁹ = 1256131397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1256131939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628065954 + 628065955.

It is an arithmetic number, because the mean of its divisors is an integer number (628065955).

Almost surely, 2^1256131909 is an apocalyptic number.

It is an amenable number.

1256131909 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256131909 is an equidigital number, since it uses as much as digits as its factorization.

1256131909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14580, while the sum is 37.

The square root of 1256131909 is about 35441.9512583605. The cubic root of 1256131909 is about 1078.9759122386.

The spelling of 1256131909 in words is "one billion, two hundred fifty-six million, one hundred thirty-one thousand, nine hundred nine".