21442386 has 32 divisors (see below), whose sum is σ = 49609728. Its totient is φ = 6051600.

The previous prime is 21442381. The next prime is 21442391. The reversal of 21442386 is 68324412.

It is an interprime number because it is at equal distance from previous prime (21442381) and next prime (21442391).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21442381) 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 15 ways as a sum of consecutive naturals, for example, 411 + ... + 6561.

It is an arithmetic number, because the mean of its divisors is an integer number (1550304).

Almost surely, 2^21442386 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21442386, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24804864).

21442386 is an abundant number, since it is smaller than the sum of its proper divisors (28167342).

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

21442386 is a wasteful number, since it uses less digits than its factorization.

21442386 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6246.

The product of its digits is 9216, while the sum is 30.

The square root of 21442386 is about 4630.5924027062. The cubic root of 21442386 is about 277.8162873662.

Adding to 21442386 its reverse (68324412), we get a palindrome (89766798).

The spelling of 21442386 in words is "twenty-one million, four hundred forty-two thousand, three hundred eighty-six".