1256406505 has 16 divisors (see below), whose sum is σ = 1603025424. Its totient is φ = 942059520.

The previous prime is 1256406467. The next prime is 1256406553. The reversal of 1256406505 is 5056046521.

It can be written as a sum of positive squares in 8 ways, for example, as 319801689 + 936604816 = 17883^2 + 30604^2 .

It is not a de Polignac number, because 1256406505 - 2¹⁵ = 1256373737 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10182 + ... + 51151.

It is an arithmetic number, because the mean of its divisors is an integer number (100189089).

Almost surely, 2^1256406505 is an apocalyptic number.

It is an amenable number.

1256406505 is a deficient number, since it is larger than the sum of its proper divisors (346618919).

1256406505 is a wasteful number, since it uses less digits than its factorization.

1256406505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61596.

The product of its (nonzero) digits is 36000, while the sum is 34.

The square root of 1256406505 is about 35445.8249304484. The cubic root of 1256406505 is about 1079.0545294816.

The spelling of 1256406505 in words is "one billion, two hundred fifty-six million, four hundred six thousand, five hundred five".