256862640 has 80 divisors (see below), whose sum is σ = 797948928. Its totient is φ = 68352768.

The previous prime is 256862629. The next prime is 256862647. The reversal of 256862640 is 46268652.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (256862647) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 163137 + ... + 164703.

Almost surely, 2^256862640 is an apocalyptic number.

256862640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256862640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (398974464).

256862640 is an abundant number, since it is smaller than the sum of its proper divisors (541086288).

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

256862640 is a wasteful number, since it uses less digits than its factorization.

256862640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2266 (or 2260 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 39.

The square root of 256862640 is about 16026.9348285940. The cubic root of 256862640 is about 635.6728272541.

The spelling of 256862640 in words is "two hundred fifty-six million, eight hundred sixty-two thousand, six hundred forty".