278661880 has 64 divisors (see below), whose sum is σ = 718165440. Its totient is φ = 95327232.

The previous prime is 278661869. The next prime is 278661881. The reversal of 278661880 is 88166872.

It is a self number, because there is not a number n which added to its sum of digits gives 278661880.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (278661881) 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, 171954 + ... + 173566.

It is an arithmetic number, because the mean of its divisors is an integer number (11221335).

Almost surely, 2^278661880 is an apocalyptic number.

278661880 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 278661880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (359082720).

278661880 is an abundant number, since it is smaller than the sum of its proper divisors (439503560).

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

278661880 is a wasteful number, since it uses less digits than its factorization.

278661880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2248 (or 2244 counting only the distinct ones).

The product of its (nonzero) digits is 258048, while the sum is 46.

The square root of 278661880 is about 16693.1686626596. The cubic root of 278661880 is about 653.1694357258.

The spelling of 278661880 in words is "two hundred seventy-eight million, six hundred sixty-one thousand, eight hundred eighty".