21442187 has 8 divisors (see below), whose sum is σ = 24095904. Its totient is φ = 18931968.

The previous prime is 21442163. The next prime is 21442229. The reversal of 21442187 is 78124412.

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

It is a cyclic number.

It is not a de Polignac number, because 21442187 - 2¹⁶ = 21376651 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21442087) 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 7 ways as a sum of consecutive naturals, for example, 35558 + ... + 36155.

It is an arithmetic number, because the mean of its divisors is an integer number (3011988).

Almost surely, 2^21442187 is an apocalyptic number.

21442187 is a deficient number, since it is larger than the sum of its proper divisors (2653717).

21442187 is a wasteful number, since it uses less digits than its factorization.

21442187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71749.

The product of its digits is 3584, while the sum is 29.

The square root of 21442187 is about 4630.5709151248. The cubic root of 21442187 is about 277.8154279218.

Adding to 21442187 its reverse (78124412), we get a palindrome (99566599).

The spelling of 21442187 in words is "twenty-one million, four hundred forty-two thousand, one hundred eighty-seven".