256155535221 has 16 divisors (see below), whose sum is σ = 350010181248. Its totient is φ = 166538937600.

The previous prime is 256155535217. The next prime is 256155535243. The reversal of 256155535221 is 122535551652.

It is not a de Polignac number, because 256155535221 - 2² = 256155535217 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256155535261) 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, 102961 + ... + 723126.

It is an arithmetic number, because the mean of its divisors is an integer number (21875636328).

Almost surely, 2^256155535221 is an apocalyptic number.

It is an amenable number.

256155535221 is a deficient number, since it is larger than the sum of its proper divisors (93854646027).

256155535221 is a wasteful number, since it uses less digits than its factorization.

256155535221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 828652.

The product of its digits is 450000, while the sum is 42.

The spelling of 256155535221 in words is "two hundred fifty-six billion, one hundred fifty-five million, five hundred thirty-five thousand, two hundred twenty-one".