687639457 has 4 divisors (see below), whose sum is σ = 688158976. Its totient is φ = 687119940.

The previous prime is 687639451. The next prime is 687639509. The reversal of 687639457 is 754936786.

It is a happy number.

687639457 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 687639457 - 2²³ = 679250849 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 687639398 and 687639407.

It is not an unprimeable number, because it can be changed into a prime (687639451) 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, 257769 + ... + 260422.

It is an arithmetic number, because the mean of its divisors is an integer number (172039744).

Almost surely, 2^687639457 is an apocalyptic number.

It is an amenable number.

687639457 is a deficient number, since it is larger than the sum of its proper divisors (519519).

687639457 is a wasteful number, since it uses less digits than its factorization.

687639457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 519518.

The product of its digits is 7620480, while the sum is 55.

The square root of 687639457 is about 26222.8804100541. The cubic root of 687639457 is about 882.6467563772.

The spelling of 687639457 in words is "six hundred eighty-seven million, six hundred thirty-nine thousand, four hundred fifty-seven".