256172217 has 8 divisors (see below), whose sum is σ = 390357696. Its totient is φ = 146384112.

The previous prime is 256172209. The next prime is 256172221. The reversal of 256172217 is 712271652.

256172217 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 256172217 - 2³ = 256172209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (256172207) 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, 6099318 + ... + 6099359.

It is an arithmetic number, because the mean of its divisors is an integer number (48794712).

Almost surely, 2^256172217 is an apocalyptic number.

It is an amenable number.

256172217 is a deficient number, since it is larger than the sum of its proper divisors (134185479).

256172217 is a wasteful number, since it uses less digits than its factorization.

256172217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12198687.

The product of its digits is 11760, while the sum is 33.

The square root of 256172217 is about 16005.3808764428. The cubic root of 256172217 is about 635.1027729578.

The spelling of 256172217 in words is "two hundred fifty-six million, one hundred seventy-two thousand, two hundred seventeen".