687181639 has 2 divisors, whose sum is σ = 687181640. Its totient is φ = 687181638.

The previous prime is 687181613. The next prime is 687181661. The reversal of 687181639 is 936181786.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 687181639 - 2⁹ = 687181127 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 687181592 and 687181601.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687181669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343590819 + 343590820.

It is an arithmetic number, because the mean of its divisors is an integer number (343590820).

Almost surely, 2^687181639 is an apocalyptic number.

687181639 is a deficient number, since it is larger than the sum of its proper divisors (1).

687181639 is an equidigital number, since it uses as much as digits as its factorization.

687181639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 435456, while the sum is 49.

The square root of 687181639 is about 26214.1495952091. The cubic root of 687181639 is about 882.4508294368.

The spelling of 687181639 in words is "six hundred eighty-seven million, one hundred eighty-one thousand, six hundred thirty-nine".