1256512399 has 2 divisors, whose sum is σ = 1256512400. Its totient is φ = 1256512398.

The previous prime is 1256512391. The next prime is 1256512403. The reversal of 1256512399 is 9932156521.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1256512399 - 2³ = 1256512391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1256512391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628256199 + 628256200.

It is an arithmetic number, because the mean of its divisors is an integer number (628256200).

Almost surely, 2^1256512399 is an apocalyptic number.

1256512399 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256512399 is an equidigital number, since it uses as much as digits as its factorization.

1256512399 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145800, while the sum is 43.

The square root of 1256512399 is about 35447.3186433050. The cubic root of 1256512399 is about 1079.0848440308.

It can be divided in two parts, 12565 and 12399, that added together give a square (24964 = 158²).

The spelling of 1256512399 in words is "one billion, two hundred fifty-six million, five hundred twelve thousand, three hundred ninety-nine".