256645641 has 16 divisors (see below), whose sum is σ = 396032000. Its totient is φ = 144797328.

The previous prime is 256645633. The next prime is 256645667. The reversal of 256645641 is 146546652.

It is not a de Polignac number, because 256645641 - 2³ = 256645633 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 256645641.

It is not an unprimeable number, because it can be changed into a prime (256645601) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 75691 + ... + 79008.

It is an arithmetic number, because the mean of its divisors is an integer number (24752000).

Almost surely, 2^256645641 is an apocalyptic number.

256645641 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

256645641 is a deficient number, since it is larger than the sum of its proper divisors (139386359).

256645641 is a wasteful number, since it uses less digits than its factorization.

256645641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154788.

The product of its digits is 172800, while the sum is 39.

The square root of 256645641 is about 16020.1635759439. The cubic root of 256645641 is about 635.4937701643.

The spelling of 256645641 in words is "two hundred fifty-six million, six hundred forty-five thousand, six hundred forty-one".