1256780257 has 8 divisors (see below), whose sum is σ = 1289545992. Its totient is φ = 1224115200.

The previous prime is 1256780243. The next prime is 1256780281. The reversal of 1256780257 is 7520876521.

It can be written as a sum of positive squares in 4 ways, for example, as 3549456 + 1253230801 = 1884^2 + 35401^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1256780257 - 2¹¹ = 1256778209 is a prime.

It is a super-2 number, since 2×1256780257² = 3158993228769972098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1256780557) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 457 + ... + 50137.

It is an arithmetic number, because the mean of its divisors is an integer number (161193249).

Almost surely, 2^1256780257 is an apocalyptic number.

It is an amenable number.

1256780257 is a deficient number, since it is larger than the sum of its proper divisors (32765735).

1256780257 is an equidigital number, since it uses as much as digits as its factorization.

1256780257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50339.

The product of its (nonzero) digits is 235200, while the sum is 43.

The square root of 1256780257 is about 35451.0966967173. The cubic root of 1256780257 is about 1079.1615168308.

The spelling of 1256780257 in words is "one billion, two hundred fifty-six million, seven hundred eighty thousand, two hundred fifty-seven".