256615505 has 4 divisors (see below), whose sum is σ = 307938612. Its totient is φ = 205292400.

The previous prime is 256615487. The next prime is 256615523. The reversal of 256615505 is 505516652.

256615505 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is an interprime number because it is at equal distance from previous prime (256615487) and next prime (256615523).

It can be written as a sum of positive squares in 2 ways, for example, as 99840064 + 156775441 = 9992^2 + 12521^2 .

It is not a de Polignac number, because 256615505 - 2¹² = 256611409 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25661546 + ... + 25661555.

It is an arithmetic number, because the mean of its divisors is an integer number (76984653).

Almost surely, 2^256615505 is an apocalyptic number.

It is an amenable number.

256615505 is a deficient number, since it is larger than the sum of its proper divisors (51323107).

256615505 is an equidigital number, since it uses as much as digits as its factorization.

256615505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51323106.

The product of its (nonzero) digits is 45000, while the sum is 35.

The square root of 256615505 is about 16019.2229836531. Note that the first 3 decimals coincide. The cubic root of 256615505 is about 635.4688954125.

The spelling of 256615505 in words is "two hundred fifty-six million, six hundred fifteen thousand, five hundred five".