21442385 has 8 divisors (see below), whose sum is σ = 26358696. Its totient is φ = 16735360.

The previous prime is 21442381. The next prime is 21442391. The reversal of 21442385 is 58324412.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 61009 + 21381376 = 247^2 + 4624^2 .

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

It is not a de Polignac number, because 21442385 - 2² = 21442381 is a prime.

It is a Duffinian 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 7 ways as a sum of consecutive naturals, for example, 52094 + ... + 52503.

It is an arithmetic number, because the mean of its divisors is an integer number (3294837).

Almost surely, 2^21442385 is an apocalyptic number.

It is an amenable number.

21442385 is a deficient number, since it is larger than the sum of its proper divisors (4916311).

21442385 is a wasteful number, since it uses less digits than its factorization.

21442385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104643.

The product of its digits is 7680, while the sum is 29.

The square root of 21442385 is about 4630.5922947286. The cubic root of 21442385 is about 277.8162830474.

Adding to 21442385 its reverse (58324412), we get a palindrome (79766797).

The spelling of 21442385 in words is "twenty-one million, four hundred forty-two thousand, three hundred eighty-five".