1256938257 has 4 divisors (see below), whose sum is σ = 1675917680. Its totient is φ = 837958836.

The previous prime is 1256938253. The next prime is 1256938261. The reversal of 1256938257 is 7528396521.

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 an emirpimes, since its reverse is a distinct semiprime: 7528396521 = 3 ⋅2509465507.

It is an interprime number because it is at equal distance from previous prime (1256938253) and next prime (1256938261).

It is not a de Polignac number, because 1256938257 - 2² = 1256938253 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1256938253) 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, 209489707 + ... + 209489712.

It is an arithmetic number, because the mean of its divisors is an integer number (418979420).

Almost surely, 2^1256938257 is an apocalyptic number.

It is an amenable number.

1256938257 is a deficient number, since it is larger than the sum of its proper divisors (418979423).

1256938257 is an equidigital number, since it uses as much as digits as its factorization.

1256938257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 418979422.

The product of its digits is 907200, while the sum is 48.

The square root of 1256938257 is about 35453.3250485762. The cubic root of 1256938257 is about 1079.2067383069.

The spelling of 1256938257 in words is "one billion, two hundred fifty-six million, nine hundred thirty-eight thousand, two hundred fifty-seven".