278805640 has 64 divisors (see below), whose sum is σ = 641986560. Its totient is φ = 108944640.

The previous prime is 278805581. The next prime is 278805649. The reversal of 278805640 is 46508872.

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 = 278805593 and 278805602.

It is not an unprimeable number, because it can be changed into a prime (278805649) 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, 360294 + ... + 361066.

It is an arithmetic number, because the mean of its divisors is an integer number (10031040).

Almost surely, 2^278805640 is an apocalyptic number.

278805640 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 278805640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (320993280).

278805640 is an abundant number, since it is smaller than the sum of its proper divisors (363180920).

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

278805640 is a wasteful number, since it uses less digits than its factorization.

278805640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 982 (or 978 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 40.

The square root of 278805640 is about 16697.4740604679. The cubic root of 278805640 is about 653.2817384865.

The spelling of 278805640 in words is "two hundred seventy-eight million, eight hundred five thousand, six hundred forty".