18691686 has 72 divisors (see below), whose sum is σ = 45894576. Its totient is φ = 5464800.

The previous prime is 18691679. The next prime is 18691693. The reversal of 18691686 is 68619681.

18691686 = 819² + 820² + ... + 845².

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (18691679) and next prime (18691693).

Its product of digits (124416) is a multiple of the sum of its prime divisors (192).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 123711 + ... + 123861.

Almost surely, 2^18691686 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18691686, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22947288).

18691686 is an abundant number, since it is smaller than the sum of its proper divisors (27202890).

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

18691686 is a wasteful number, since it uses less digits than its factorization.

18691686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218 (or 192 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 18691686 is about 4323.3882545985. The cubic root of 18691686 is about 265.3889435192.

The spelling of 18691686 in words is "eighteen million, six hundred ninety-one thousand, six hundred eighty-six".