255687978 has 128 divisors (see below), whose sum is σ = 677376000. Its totient is φ = 63758016.

The previous prime is 255687977. The next prime is 255687979. The reversal of 255687978 is 879786552.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (255687977) and next prime (255687979).

It is a Harshad number since it is a multiple of its sum of digits (57).

It is not an unprimeable number, because it can be changed into a prime (255687977) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 508075 + ... + 508577.

It is an arithmetic number, because the mean of its divisors is an integer number (5292000).

Almost surely, 2^255687978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 255687978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (338688000).

255687978 is an abundant number, since it is smaller than the sum of its proper divisors (421688022).

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

255687978 is a wasteful number, since it uses less digits than its factorization.

255687978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 561 (or 547 counting only the distinct ones).

The product of its digits is 8467200, while the sum is 57.

The square root of 255687978 is about 15990.2463395659. The cubic root of 255687978 is about 634.7023450483.

The spelling of 255687978 in words is "two hundred fifty-five million, six hundred eighty-seven thousand, nine hundred seventy-eight".