1256643511 has 2 divisors, whose sum is σ = 1256643512. Its totient is φ = 1256643510.

The previous prime is 1256643499. The next prime is 1256643533. The reversal of 1256643511 is 1153466521.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1256643511 - 2¹⁹ = 1256119223 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1256643541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628321755 + 628321756.

It is an arithmetic number, because the mean of its divisors is an integer number (628321756).

Almost surely, 2^1256643511 is an apocalyptic number.

1256643511 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256643511 is an equidigital number, since it uses as much as digits as its factorization.

1256643511 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21600, while the sum is 34.

The square root of 1256643511 is about 35449.1679874154. The cubic root of 1256643511 is about 1079.1223754422.

The spelling of 1256643511 in words is "one billion, two hundred fifty-six million, six hundred forty-three thousand, five hundred eleven".