687921079 has 4 divisors (see below), whose sum is σ = 700900776. Its totient is φ = 674941384.

The previous prime is 687921067. The next prime is 687921097. The reversal of 687921079 is 970129786.

It is a happy number.

687921079 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 687921079 - 2⁹ = 687920567 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687921979) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6489769 + ... + 6489874.

It is an arithmetic number, because the mean of its divisors is an integer number (175225194).

Almost surely, 2^687921079 is an apocalyptic number.

687921079 is a deficient number, since it is larger than the sum of its proper divisors (12979697).

687921079 is a wasteful number, since it uses less digits than its factorization.

687921079 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12979696.

The product of its (nonzero) digits is 381024, while the sum is 49.

The square root of 687921079 is about 26228.2496366037. The cubic root of 687921079 is about 882.7672356079.

The spelling of 687921079 in words is "six hundred eighty-seven million, nine hundred twenty-one thousand, seventy-nine".