256909721672 has 12 divisors (see below), whose sum is σ = 481708416195. Its totient is φ = 128454144024.

The previous prime is 256909721659. The next prime is 256909721807. The reversal of 256909721672 is 276127909652.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in only one way, i.e., 128454860836 + 128454860836 = 358406^2 + 358406^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=358406.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1344023 + ... + 1523225.

Almost surely, 2^256909721672 is an apocalyptic number.

It is an amenable number.

256909721672 is a deficient number, since it is larger than the sum of its proper divisors (224798694523).

256909721672 is an frugal number, since it uses more digits than its factorization.

256909721672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358412 (or 179205 counting only the distinct ones).

The product of its (nonzero) digits is 5715360, while the sum is 56.

The spelling of 256909721672 in words is "two hundred fifty-six billion, nine hundred nine million, seven hundred twenty-one thousand, six hundred seventy-two".