687721487 has 2 divisors, whose sum is σ = 687721488. Its totient is φ = 687721486.

The previous prime is 687721429. The next prime is 687721499. The reversal of 687721487 is 784127786.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 687721487 - 2¹⁰ = 687720463 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687721427) 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, 343860743 + 343860744.

It is an arithmetic number, because the mean of its divisors is an integer number (343860744).

Almost surely, 2^687721487 is an apocalyptic number.

687721487 is a deficient number, since it is larger than the sum of its proper divisors (1).

687721487 is an equidigital number, since it uses as much as digits as its factorization.

687721487 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1053696, while the sum is 50.

The square root of 687721487 is about 26224.4444555075. Note that the first 4 decimals coincide. The cubic root of 687721487 is about 882.6818525961.

The spelling of 687721487 in words is "six hundred eighty-seven million, seven hundred twenty-one thousand, four hundred eighty-seven".