688916749 has 4 divisors (see below), whose sum is σ = 688989564. Its totient is φ = 688843936.

The previous prime is 688916743. The next prime is 688916759. The reversal of 688916749 is 947619886.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 368256100 + 320660649 = 19190^2 + 17907^2 .

It is a cyclic number.

It is not a de Polignac number, because 688916749 - 2²¹ = 686819597 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 688916693 and 688916702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688916743) 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, 19642 + ... + 41995.

It is an arithmetic number, because the mean of its divisors is an integer number (172247391).

Almost surely, 2^688916749 is an apocalyptic number.

It is an amenable number.

688916749 is a deficient number, since it is larger than the sum of its proper divisors (72815).

688916749 is a wasteful number, since it uses less digits than its factorization.

688916749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72814.

The product of its digits is 5225472, while the sum is 58.

The square root of 688916749 is about 26247.2236436542. The cubic root of 688916749 is about 883.1929245282.

The spelling of 688916749 in words is "six hundred eighty-eight million, nine hundred sixteen thousand, seven hundred forty-nine".