21442164 has 24 divisors (see below), whose sum is σ = 52207680. Its totient is φ = 6836544.

The previous prime is 21442163. The next prime is 21442229. The reversal of 21442164 is 46124412.

It is a happy number.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21442163) 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, 38569 + ... + 39120.

It is an arithmetic number, because the mean of its divisors is an integer number (2175320).

Almost surely, 2^21442164 is an apocalyptic number.

It is an amenable number.

21442164 is an abundant number, since it is smaller than the sum of its proper divisors (30765516).

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

21442164 is a wasteful number, since it uses less digits than its factorization.

21442164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77719 (or 77717 counting only the distinct ones).

The product of its digits is 1536, while the sum is 24.

The square root of 21442164 is about 4630.5684316291. The cubic root of 21442164 is about 277.8153285887.

Adding to 21442164 its reverse (46124412), we get a palindrome (67566576).

The spelling of 21442164 in words is "twenty-one million, four hundred forty-two thousand, one hundred sixty-four".