280387640 has 32 divisors (see below), whose sum is σ = 679402080. Its totient is φ = 103527552.

The previous prime is 280387637. The next prime is 280387651. The reversal of 280387640 is 46783082.

It is a junction number, because it is equal to n+sod(n) for n = 280387594 and 280387603.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 269084 + ... + 270123.

It is an arithmetic number, because the mean of its divisors is an integer number (21231315).

Almost surely, 2^280387640 is an apocalyptic number.

280387640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

280387640 is an abundant number, since it is smaller than the sum of its proper divisors (399014440).

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

280387640 is a wasteful number, since it uses less digits than its factorization.

280387640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 539231 (or 539227 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 38.

The square root of 280387640 is about 16744.7794849619. The cubic root of 280387640 is about 654.5150266673.

The spelling of 280387640 in words is "two hundred eighty million, three hundred eighty-seven thousand, six hundred forty".