256786686 has 40 divisors (see below), whose sum is σ = 619658424. Its totient is φ = 79010640.

The previous prime is 256786613. The next prime is 256786687. The reversal of 256786686 is 686687652.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256786687) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 58860 + ... + 63071.

Almost surely, 2^256786686 is an apocalyptic number.

256786686 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

256786686 is an abundant number, since it is smaller than the sum of its proper divisors (362871738).

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

256786686 is a wasteful number, since it uses less digits than its factorization.

256786686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121958 (or 121949 counting only the distinct ones).

The product of its digits is 5806080, while the sum is 54.

The square root of 256786686 is about 16024.5650799015. The cubic root of 256786686 is about 635.6101651588.

It can be divided in two parts, 2567 and 86686, that added together give a triangular number (89253 = T₄₂₂).

The spelling of 256786686 in words is "two hundred fifty-six million, seven hundred eighty-six thousand, six hundred eighty-six".