686696621 has 8 divisors (see below), whose sum is σ = 746305560. Its totient is φ = 628057152.

The previous prime is 686696617. The next prime is 686696639. The reversal of 686696621 is 126696686.

686696621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 120780100 + 565916521 = 10990^2 + 23789^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 686696621 - 2² = 686696617 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 686696621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686696821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 240890 + ... + 243723.

It is an arithmetic number, because the mean of its divisors is an integer number (93288195).

Almost surely, 2^686696621 is an apocalyptic number.

It is an amenable number.

686696621 is a deficient number, since it is larger than the sum of its proper divisors (59608939).

686696621 is a wasteful number, since it uses less digits than its factorization.

686696621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 484735.

The product of its digits is 1119744, while the sum is 50.

The square root of 686696621 is about 26204.8968897036. The cubic root of 686696621 is about 882.2431670819.

The spelling of 686696621 in words is "six hundred eighty-six million, six hundred ninety-six thousand, six hundred twenty-one".