688020139 has 4 divisors (see below), whose sum is σ = 704801160. Its totient is φ = 671239120.

The previous prime is 688020131. The next prime is 688020163. The reversal of 688020139 is 931020886.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 688020139 - 2³ = 688020131 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 688020098 and 688020107.

It is not an unprimeable number, because it can be changed into a prime (688020131) 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 in 3 ways as a sum of consecutive naturals, for example, 8390449 + ... + 8390530.

It is an arithmetic number, because the mean of its divisors is an integer number (176200290).

Almost surely, 2^688020139 is an apocalyptic number.

688020139 is a deficient number, since it is larger than the sum of its proper divisors (16781021).

688020139 is a wasteful number, since it uses less digits than its factorization.

688020139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16781020.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 688020139 is about 26230.1379904872. The cubic root of 688020139 is about 882.8096061298.

The spelling of 688020139 in words is "six hundred eighty-eight million, twenty thousand, one hundred thirty-nine".