781987 has 2 divisors, whose sum is σ = 781988. Its totient is φ = 781986.

The previous prime is 781973. The next prime is 781997. The reversal of 781987 is 789187.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 781987 - 2¹¹ = 779939 is a prime.

It is a super-2 number, since 2×781987² = 1223007336338, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (781967) 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 as a sum of consecutive naturals, namely, 390993 + 390994.

It is an arithmetic number, because the mean of its divisors is an integer number (390994).

2⁷⁸¹⁹⁸⁷ is an apocalyptic number.

781987 is a deficient number, since it is larger than the sum of its proper divisors (1).

781987 is an equidigital number, since it uses as much as digits as its factorization.

781987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 28224, while the sum is 40.

The square root of 781987 is about 884.3002883636. The cubic root of 781987 is about 92.1297397634.

The spelling of 781987 in words is "seven hundred eighty-one thousand, nine hundred eighty-seven".