688712905 has 4 divisors (see below), whose sum is σ = 826455492. Its totient is φ = 550970320.

The previous prime is 688712881. The next prime is 688712923. The reversal of 688712905 is 509217886.

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

It can be written as a sum of positive squares in 2 ways, for example, as 309865609 + 378847296 = 17603^2 + 19464^2 .

It is not a de Polignac number, because 688712905 - 2¹³ = 688704713 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68871286 + ... + 68871295.

It is an arithmetic number, because the mean of its divisors is an integer number (206613873).

Almost surely, 2^688712905 is an apocalyptic number.

It is an amenable number.

688712905 is a deficient number, since it is larger than the sum of its proper divisors (137742587).

688712905 is a wasteful number, since it uses less digits than its factorization.

688712905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137742586.

The product of its (nonzero) digits is 241920, while the sum is 46.

The square root of 688712905 is about 26243.3402028019. The cubic root of 688712905 is about 883.1058064362.

The spelling of 688712905 in words is "six hundred eighty-eight million, seven hundred twelve thousand, nine hundred five".