1256340889 has 4 divisors (see below), whose sum is σ = 1256450256. Its totient is φ = 1256231524.

The previous prime is 1256340859. The next prime is 1256340907. The reversal of 1256340889 is 9880436521.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 9880436521 = 63901 ⋅154621.

It is a cyclic number.

It is not a de Polignac number, because 1256340889 - 2⁹ = 1256340377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1256340859) 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, 35119 + ... + 61204.

It is an arithmetic number, because the mean of its divisors is an integer number (314112564).

Almost surely, 2^1256340889 is an apocalyptic number.

It is an amenable number.

1256340889 is a deficient number, since it is larger than the sum of its proper divisors (109367).

1256340889 is an equidigital number, since it uses as much as digits as its factorization.

1256340889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109366.

The product of its (nonzero) digits is 414720, while the sum is 46.

The square root of 1256340889 is about 35444.8993368580. The cubic root of 1256340889 is about 1079.0357445649.

The spelling of 1256340889 in words is "one billion, two hundred fifty-six million, three hundred forty thousand, eight hundred eighty-nine".