280987991 has 2 divisors, whose sum is σ = 280987992. Its totient is φ = 280987990.

The previous prime is 280987963. The next prime is 280987997. The reversal of 280987991 is 199789082.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-280987991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (280987997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 140493995 + 140493996.

It is an arithmetic number, because the mean of its divisors is an integer number (140493996).

Almost surely, 2^280987991 is an apocalyptic number.

280987991 is a deficient number, since it is larger than the sum of its proper divisors (1).

280987991 is an equidigital number, since it uses as much as digits as its factorization.

280987991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 653184, while the sum is 53.

The square root of 280987991 is about 16762.6964119738. The cubic root of 280987991 is about 654.9818311686.

The spelling of 280987991 in words is "two hundred eighty million, nine hundred eighty-seven thousand, nine hundred ninety-one".