256517109 has 12 divisors (see below), whose sum is σ = 375601356. Its totient is φ = 168668352.

The previous prime is 256517101. The next prime is 256517111. The reversal of 256517109 is 901715652.

It can be written as a sum of positive squares in 2 ways, for example, as 114383025 + 142134084 = 10695^2 + 11922^2 .

It is not a de Polignac number, because 256517109 - 2³ = 256517101 is a prime.

It is a super-4 number, since 4×256517109⁴ (a number of 35 digits) contains 4444 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256517101) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 194562 + ... + 195875.

It is an arithmetic number, because the mean of its divisors is an integer number (31300113).

Almost surely, 2^256517109 is an apocalyptic number.

It is an amenable number.

256517109 is a deficient number, since it is larger than the sum of its proper divisors (119084247).

256517109 is a wasteful number, since it uses less digits than its factorization.

256517109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390516 (or 390513 counting only the distinct ones).

The product of its (nonzero) digits is 18900, while the sum is 36.

The square root of 256517109 is about 16016.1515040287. The cubic root of 256517109 is about 635.3876641674.

The spelling of 256517109 in words is "two hundred fifty-six million, five hundred seventeen thousand, one hundred nine".