687838939 has 2 divisors, whose sum is σ = 687838940. Its totient is φ = 687838938.

The previous prime is 687838913. The next prime is 687838961. The reversal of 687838939 is 939838786.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 687838939 - 2²⁵ = 654284507 is a prime.

It is not a weakly prime, because it can be changed into another prime (687838979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343919469 + 343919470.

It is an arithmetic number, because the mean of its divisors is an integer number (343919470).

Almost surely, 2^687838939 is an apocalyptic number.

687838939 is a deficient number, since it is larger than the sum of its proper divisors (1).

687838939 is an equidigital number, since it uses as much as digits as its factorization.

687838939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15676416, while the sum is 61.

The square root of 687838939 is about 26226.6837209740. The cubic root of 687838939 is about 882.7320991225.

The spelling of 687838939 in words is "six hundred eighty-seven million, eight hundred thirty-eight thousand, nine hundred thirty-nine".