256731396091 has 4 divisors (see below), whose sum is σ = 257164333272. Its totient is φ = 256298458912.

The previous prime is 256731396067. The next prime is 256731396107. The reversal of 256731396091 is 190693137652.

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

It is a cyclic number.

It is not a de Polignac number, because 256731396091 - 2¹¹ = 256731394043 is a prime.

It is a super-2 number, since 2×256731396091² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256731396001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 216467701 + ... + 216468886.

It is an arithmetic number, because the mean of its divisors is an integer number (64291083318).

Almost surely, 2^256731396091 is an apocalyptic number.

256731396091 is a deficient number, since it is larger than the sum of its proper divisors (432937181).

256731396091 is an equidigital number, since it uses as much as digits as its factorization.

256731396091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432937180.

The product of its (nonzero) digits is 1837080, while the sum is 52.

The spelling of 256731396091 in words is "two hundred fifty-six billion, seven hundred thirty-one million, three hundred ninety-six thousand, ninety-one".