256163505 has 32 divisors (see below), whose sum is σ = 442315776. Its totient is φ = 125846784.

The previous prime is 256163483. The next prime is 256163519. The reversal of 256163505 is 505361652.

It is not a de Polignac number, because 256163505 - 2⁶ = 256163441 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 118464 + ... + 120606.

It is an arithmetic number, because the mean of its divisors is an integer number (13822368).

Almost surely, 2^256163505 is an apocalyptic number.

It is an amenable number.

256163505 is a deficient number, since it is larger than the sum of its proper divisors (186152271).

256163505 is a wasteful number, since it uses less digits than its factorization.

256163505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2777.

The product of its (nonzero) digits is 27000, while the sum is 33.

The square root of 256163505 is about 16005.1087156570. The cubic root of 256163505 is about 635.0955732725.

It can be divided in two parts, 2561 and 63505, that added together give a palindrome (66066).

The spelling of 256163505 in words is "two hundred fifty-six million, one hundred sixty-three thousand, five hundred five".