1256259891 has 4 divisors (see below), whose sum is σ = 1675013192. Its totient is φ = 837506592.

The previous prime is 1256259889. The next prime is 1256259943. The reversal of 1256259891 is 1989526521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1989526521 = 3 ⋅663175507.

It is not a de Polignac number, because 1256259891 - 2¹ = 1256259889 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1256259891.

It is not an unprimeable number, because it can be changed into a prime (1256259811) 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, 209376646 + ... + 209376651.

It is an arithmetic number, because the mean of its divisors is an integer number (418753298).

Almost surely, 2^1256259891 is an apocalyptic number.

1256259891 is a deficient number, since it is larger than the sum of its proper divisors (418753301).

1256259891 is an equidigital number, since it uses as much as digits as its factorization.

1256259891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 418753300.

The product of its digits is 388800, while the sum is 48.

The square root of 1256259891 is about 35443.7567280896. The cubic root of 1256259891 is about 1079.0125551009.

The spelling of 1256259891 in words is "one billion, two hundred fifty-six million, two hundred fifty-nine thousand, eight hundred ninety-one".