256609840 has 20 divisors (see below), whose sum is σ = 596618064. Its totient is φ = 102643904.

The previous prime is 256609831. The next prime is 256609867. The reversal of 256609840 is 48906652.

It is a happy number.

256609840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 256609793 and 256609802.

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, 1603732 + ... + 1603891.

Almost surely, 2^256609840 is an apocalyptic number.

256609840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256609840 is an abundant number, since it is smaller than the sum of its proper divisors (340008224).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256609840 is a wasteful number, since it uses less digits than its factorization.

256609840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3207636 (or 3207630 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 40.

The square root of 256609840 is about 16019.0461638638. The cubic root of 256609840 is about 635.4642192105.

The spelling of 256609840 in words is "two hundred fifty-six million, six hundred nine thousand, eight hundred forty".