256540069 has 4 divisors (see below), whose sum is σ = 256617900. Its totient is φ = 256462240.

The previous prime is 256540043. The next prime is 256540073. The reversal of 256540069 is 960045652.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 40832100 + 215707969 = 6390^2 + 14687^2 .

It is a cyclic number.

It is not a de Polignac number, because 256540069 - 2²¹ = 254442917 is a prime.

It is a super-2 number, since 2×256540069² = 131625614005049522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256540019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33742 + ... + 40639.

It is an arithmetic number, because the mean of its divisors is an integer number (64154475).

Almost surely, 2^256540069 is an apocalyptic number.

It is an amenable number.

256540069 is a deficient number, since it is larger than the sum of its proper divisors (77831).

256540069 is an equidigital number, since it uses as much as digits as its factorization.

256540069 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77830.

The product of its (nonzero) digits is 64800, while the sum is 37.

The square root of 256540069 is about 16016.8682644267. The cubic root of 256540069 is about 635.4066207529.

The spelling of 256540069 in words is "two hundred fifty-six million, five hundred forty thousand, sixty-nine".