1256851591 has 2 divisors, whose sum is σ = 1256851592. Its totient is φ = 1256851590.

The previous prime is 1256851567. The next prime is 1256851637. The reversal of 1256851591 is 1951586521.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1256851591 - 2⁵ = 1256851559 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1256851091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628425795 + 628425796.

It is an arithmetic number, because the mean of its divisors is an integer number (628425796).

Almost surely, 2^1256851591 is an apocalyptic number.

1256851591 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256851591 is an equidigital number, since it uses as much as digits as its factorization.

1256851591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108000, while the sum is 43.

The square root of 1256851591 is about 35452.1027726142. The cubic root of 1256851591 is about 1079.1819339379.

The spelling of 1256851591 in words is "one billion, two hundred fifty-six million, eight hundred fifty-one thousand, five hundred ninety-one".