21186042 has 8 divisors (see below), whose sum is σ = 42372096. Its totient is φ = 7062012.

The previous prime is 21186041. The next prime is 21186071. The reversal of 21186042 is 24068112.

It is a sphenic number, since it is the product of 3 distinct primes.

21186042 is an admirable number.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21186041) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1765498 + ... + 1765509.

It is an arithmetic number, because the mean of its divisors is an integer number (5296512).

Almost surely, 2^21186042 is an apocalyptic number.

21186042 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21186042 is a wasteful number, since it uses less digits than its factorization.

21186042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3531012.

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 21186042 is about 4602.8297817756. The cubic root of 21186042 is about 276.7047469398.

The spelling of 21186042 in words is "twenty-one million, one hundred eighty-six thousand, forty-two".