256135641646 has 4 divisors (see below), whose sum is σ = 384203462472. Its totient is φ = 128067820822.

The previous prime is 256135641631. The next prime is 256135641653. The reversal of 256135641646 is 646146531652.

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

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 256135641646.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64033910410 + ... + 64033910413.

It is an arithmetic number, because the mean of its divisors is an integer number (96050865618).

Almost surely, 2^256135641646 is an apocalyptic number.

256135641646 is a deficient number, since it is larger than the sum of its proper divisors (128067820826).

256135641646 is a wasteful number, since it uses less digits than its factorization.

256135641646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128067820825.

The product of its digits is 3110400, while the sum is 49.

The spelling of 256135641646 in words is "two hundred fifty-six billion, one hundred thirty-five million, six hundred forty-one thousand, six hundred forty-six".