1256431157 has 2 divisors, whose sum is σ = 1256431158. Its totient is φ = 1256431156.

The previous prime is 1256431073. The next prime is 1256431181. The reversal of 1256431157 is 7511346521.

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., 1025664676 + 230766481 = 32026^2 + 15191^2 .

It is a cyclic number.

It is not a de Polignac number, because 1256431157 - 2¹⁴ = 1256414773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1256131157) 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 as a sum of consecutive naturals, namely, 628215578 + 628215579.

It is an arithmetic number, because the mean of its divisors is an integer number (628215579).

Almost surely, 2^1256431157 is an apocalyptic number.

It is an amenable number.

1256431157 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256431157 is an equidigital number, since it uses as much as digits as its factorization.

1256431157 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25200, while the sum is 35.

The square root of 1256431157 is about 35446.1726706848. The cubic root of 1256431157 is about 1079.0615868255.

Adding to 1256431157 its reverse (7511346521), we get a palindrome (8767777678).

The spelling of 1256431157 in words is "one billion, two hundred fifty-six million, four hundred thirty-one thousand, one hundred fifty-seven".