1686638549 has 8 divisors (see below), whose sum is σ = 1696360248. Its totient is φ = 1676928960.

The previous prime is 1686638543. The next prime is 1686638563. The reversal of 1686638549 is 9458366861.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1370332324 + 316306225 = 37018^2 + 17785^2 .

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 1686638549 - 2⁴ = 1686638533 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1686638494 and 1686638503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1686638543) 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, 549479 + ... + 552539.

It is an arithmetic number, because the mean of its divisors is an integer number (212045031).

Almost surely, 2^1686638549 is an apocalyptic number.

It is an amenable number.

1686638549 is a deficient number, since it is larger than the sum of its proper divisors (9721699).

1686638549 is a wasteful number, since it uses less digits than its factorization.

1686638549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6055.

The product of its digits is 7464960, while the sum is 56.

The square root of 1686638549 is about 41068.7052267295. The cubic root of 1686638549 is about 1190.3481666084.

The spelling of 1686638549 in words is "one billion, six hundred eighty-six million, six hundred thirty-eight thousand, five hundred forty-nine".