21145842 has 12 divisors (see below), whose sum is σ = 45816030. Its totient is φ = 7048608.

The previous prime is 21145829. The next prime is 21145871. The reversal of 21145842 is 24854112.

It can be written as a sum of positive squares in only one way, i.e., 18740241 + 2405601 = 4329^2 + 1551^2 .

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 587367 + ... + 587402.

Almost surely, 2^21145842 is an apocalyptic number.

21145842 is an abundant number, since it is smaller than the sum of its proper divisors (24670188).

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

21145842 is a wasteful number, since it uses less digits than its factorization.

21145842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1174777 (or 1174774 counting only the distinct ones).

The product of its digits is 2560, while the sum is 27.

The square root of 21145842 is about 4598.4608294515. The cubic root of 21145842 is about 276.5296226167.

Adding to 21145842 its reverse (24854112), we get a palindrome (45999954).

The spelling of 21145842 in words is "twenty-one million, one hundred forty-five thousand, eight hundred forty-two".