21223542 has 16 divisors (see below), whose sum is σ = 42517440. Its totient is φ = 7062792.

The previous prime is 21223519. The next prime is 21223583. The reversal of 21223542 is 24532212.

It is a congruent number.

It is an unprimeable number.

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, 1509 + ... + 6687.

It is an arithmetic number, because the mean of its divisors is an integer number (2657340).

Almost surely, 2^21223542 is an apocalyptic number.

21223542 is an abundant number, since it is smaller than the sum of its proper divisors (21293898).

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

21223542 is a wasteful number, since it uses less digits than its factorization.

21223542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5867.

The product of its digits is 960, while the sum is 21.

The square root of 21223542 is about 4606.9015617875. The cubic root of 21223542 is about 276.8679095827.

Adding to 21223542 its reverse (24532212), we get a palindrome (45755754).

The spelling of 21223542 in words is "twenty-one million, two hundred twenty-three thousand, five hundred forty-two".