280785561 has 16 divisors (see below), whose sum is σ = 429004800. Its totient is φ = 160021008.

The previous prime is 280785559. The next prime is 280785641. The reversal of 280785561 is 165587082.

It is not a de Polignac number, because 280785561 - 2¹ = 280785559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (280785161) 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, 9681 + ... + 25598.

It is an arithmetic number, because the mean of its divisors is an integer number (26812800).

Almost surely, 2^280785561 is an apocalyptic number.

280785561 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

280785561 is a deficient number, since it is larger than the sum of its proper divisors (148219239).

280785561 is a wasteful number, since it uses less digits than its factorization.

280785561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35668.

The product of its (nonzero) digits is 134400, while the sum is 42.

The square root of 280785561 is about 16756.6572143730. The cubic root of 280785561 is about 654.8245055546.

The spelling of 280785561 in words is "two hundred eighty million, seven hundred eighty-five thousand, five hundred sixty-one".