686537381 has 4 divisors (see below), whose sum is σ = 686595264. Its totient is φ = 686479500.

The previous prime is 686537353. The next prime is 686537437. The reversal of 686537381 is 183735686.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 183735686 = 2 ⋅91867843.

It is a cyclic number.

It is not a de Polignac number, because 686537381 - 2¹⁸ = 686275237 is a prime.

It is a super-2 number, since 2×686537381² = 942667151020678322, 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 (686537351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3965 + ... + 37266.

It is an arithmetic number, because the mean of its divisors is an integer number (171648816).

Almost surely, 2^686537381 is an apocalyptic number.

It is an amenable number.

686537381 is a deficient number, since it is larger than the sum of its proper divisors (57883).

686537381 is a wasteful number, since it uses less digits than its factorization.

686537381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57882.

The product of its digits is 725760, while the sum is 47.

The square root of 686537381 is about 26201.8583501247. The cubic root of 686537381 is about 882.1749665314.

The spelling of 686537381 in words is "six hundred eighty-six million, five hundred thirty-seven thousand, three hundred eighty-one".