256909020081 has 8 divisors (see below), whose sum is σ = 391480411584. Its totient is φ = 146805154320.

The previous prime is 256909020079. The next prime is 256909020107. The reversal of 256909020081 is 180020909652.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 256909020081 - 2¹ = 256909020079 is a prime.

It is a super-2 number, since 2×256909020081² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (256909020041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6116881410 + ... + 6116881451.

It is an arithmetic number, because the mean of its divisors is an integer number (48935051448).

Almost surely, 2^256909020081 is an apocalyptic number.

256909020081 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

256909020081 is a deficient number, since it is larger than the sum of its proper divisors (134571391503).

256909020081 is a wasteful number, since it uses less digits than its factorization.

256909020081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12233762871.

The product of its (nonzero) digits is 77760, while the sum is 42.

The spelling of 256909020081 in words is "two hundred fifty-six billion, nine hundred nine million, twenty thousand, eighty-one".