21561142 has 16 divisors (see below), whose sum is σ = 33277392. Its totient is φ = 10472800.

The previous prime is 21561131. The next prime is 21561167. The reversal of 21561142 is 24116512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10392 + ... + 12292.

It is an arithmetic number, because the mean of its divisors is an integer number (2079837).

Almost surely, 2^21561142 is an apocalyptic number.

21561142 is a deficient number, since it is larger than the sum of its proper divisors (11716250).

21561142 is a wasteful number, since it uses less digits than its factorization.

21561142 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2063.

The product of its digits is 480, while the sum is 22.

The square root of 21561142 is about 4643.3976784247. The cubic root of 21561142 is about 278.3282271245.

Adding to 21561142 its reverse (24116512), we get a palindrome (45677654).

The spelling of 21561142 in words is "twenty-one million, five hundred sixty-one thousand, one hundred forty-two".