686581669 has 4 divisors (see below), whose sum is σ = 726968844. Its totient is φ = 646194496.

The previous prime is 686581667. The next prime is 686581691. The reversal of 686581669 is 966185686.

It is a happy number.

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 570588769 + 115992900 = 23887^2 + 10770^2 .

It is a cyclic number.

It is not a de Polignac number, because 686581669 - 2¹ = 686581667 is a prime.

It is a super-2 number, since 2×686581669² = 942788776413651122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686581661) 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, 20193562 + ... + 20193595.

It is an arithmetic number, because the mean of its divisors is an integer number (181742211).

Almost surely, 2^686581669 is an apocalyptic number.

It is an amenable number.

686581669 is a deficient number, since it is larger than the sum of its proper divisors (40387175).

686581669 is a wasteful number, since it uses less digits than its factorization.

686581669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40387174.

The product of its digits is 3732480, while the sum is 55.

The square root of 686581669 is about 26202.7034673905. The cubic root of 686581669 is about 882.1939356004.

The spelling of 686581669 in words is "six hundred eighty-six million, five hundred eighty-one thousand, six hundred sixty-nine".