21145242 has 8 divisors (see below), whose sum is σ = 42290496. Its totient is φ = 7048412.

The previous prime is 21145213. The next prime is 21145249. The reversal of 21145242 is 24254112.

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

21145242 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21145249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1762098 + ... + 1762109.

It is an arithmetic number, because the mean of its divisors is an integer number (5286312).

Almost surely, 2^21145242 is an apocalyptic number.

21145242 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.

21145242 is a wasteful number, since it uses less digits than its factorization.

21145242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3524212.

The product of its digits is 640, while the sum is 21.

The square root of 21145242 is about 4598.3955897682. The cubic root of 21145242 is about 276.5270071404.

Adding to 21145242 its reverse (24254112), we get a palindrome (45399354).

The spelling of 21145242 in words is "twenty-one million, one hundred forty-five thousand, two hundred forty-two".