687639539 has 2 divisors, whose sum is σ = 687639540. Its totient is φ = 687639538.

The previous prime is 687639517. The next prime is 687639541. The reversal of 687639539 is 935936786.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 687639539 - 2⁸ = 687639283 is a prime.

It is a super-2 number, since 2×687639539² = 945696271192265042, which contains 22 as substring.

Together with 687639541, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (687639509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343819769 + 343819770.

It is an arithmetic number, because the mean of its divisors is an integer number (343819770).

Almost surely, 2^687639539 is an apocalyptic number.

687639539 is a deficient number, since it is larger than the sum of its proper divisors (1).

687639539 is an equidigital number, since it uses as much as digits as its factorization.

687639539 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7348320, while the sum is 56.

The square root of 687639539 is about 26222.8819735741. The cubic root of 687639539 is about 882.6467914620.

The spelling of 687639539 in words is "six hundred eighty-seven million, six hundred thirty-nine thousand, five hundred thirty-nine".