20191986 has 24 divisors (see below), whose sum is σ = 43902144. Its totient is φ = 6707160.

The previous prime is 20191931. The next prime is 20191987. The reversal of 20191986 is 68919102.

It is a self number, because there is not a number n which added to its sum of digits gives 20191986.

It is not an unprimeable number, because it can be changed into a prime (20191987) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3795 + ... + 7401.

It is an arithmetic number, because the mean of its divisors is an integer number (1829256).

Almost surely, 2^20191986 is an apocalyptic number.

20191986 is an abundant number, since it is smaller than the sum of its proper divisors (23710158).

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

20191986 is a wasteful number, since it uses less digits than its factorization.

20191986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3926 (or 3923 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 20191986 is about 4493.5493766064. The cubic root of 20191986 is about 272.3075475290.

It can be divided in two parts, 2019 and 1986, that added together give a triangular number (4005 = T₈₉).

The spelling of 20191986 in words is "twenty million, one hundred ninety-one thousand, nine hundred eighty-six".