20131686 has 16 divisors (see below), whose sum is σ = 44737200. Its totient is φ = 6710544.

The previous prime is 20131681. The next prime is 20131717. The reversal of 20131686 is 68613102.

It is a super-4 number, since 4×20131686⁴ (a number of 30 digits) contains 4444 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20131681) 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, 186351 + ... + 186458.

It is an arithmetic number, because the mean of its divisors is an integer number (2796075).

Almost surely, 2^20131686 is an apocalyptic number.

20131686 is an abundant number, since it is smaller than the sum of its proper divisors (24605514).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20131686 is a wasteful number, since it uses less digits than its factorization.

20131686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372820 (or 372814 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 20131686 is about 4486.8347417751. The cubic root of 20131686 is about 272.0362102168.

Adding to 20131686 its reverse (68613102), we get a palindrome (88744788).

The spelling of 20131686 in words is "twenty million, one hundred thirty-one thousand, six hundred eighty-six".