256121005 has 16 divisors (see below), whose sum is σ = 357012864. Its totient is φ = 172745280.

The previous prime is 256120981. The next prime is 256121023. The reversal of 256121005 is 500121652.

It is a de Polignac number, because none of the positive numbers 2^k-256121005 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57847 + ... + 62116.

It is an arithmetic number, because the mean of its divisors is an integer number (22313304).

Almost surely, 2^256121005 is an apocalyptic number.

It is an amenable number.

256121005 is a deficient number, since it is larger than the sum of its proper divisors (100891859).

256121005 is a wasteful number, since it uses less digits than its factorization.

256121005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120036.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 256121005 is about 16003.7809595108. The cubic root of 256121005 is about 635.0604484997.

Adding to 256121005 its reverse (500121652), we get a palindrome (756242657).

The spelling of 256121005 in words is "two hundred fifty-six million, one hundred twenty-one thousand, five".