280139987 has 4 divisors (see below), whose sum is σ = 287711376. Its totient is φ = 272568600.

The previous prime is 280139983. The next prime is 280140011. The reversal of 280139987 is 789931082.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 789931082 = 2 ⋅394965541.

It is a cyclic number.

It is not a de Polignac number, because 280139987 - 2² = 280139983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (280139983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3785639 + ... + 3785712.

It is an arithmetic number, because the mean of its divisors is an integer number (71927844).

Almost surely, 2^280139987 is an apocalyptic number.

280139987 is a deficient number, since it is larger than the sum of its proper divisors (7571389).

280139987 is an equidigital number, since it uses as much as digits as its factorization.

280139987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7571388.

The product of its (nonzero) digits is 217728, while the sum is 47.

The square root of 280139987 is about 16737.3829196801. The cubic root of 280139987 is about 654.3222692925.

The spelling of 280139987 in words is "two hundred eighty million, one hundred thirty-nine thousand, nine hundred eighty-seven".