21424042 has 4 divisors (see below), whose sum is σ = 32136066. Its totient is φ = 10712020.

The previous prime is 21424027. The next prime is 21424049. The reversal of 21424042 is 24042412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 13756681 + 7667361 = 3709^2 + 2769^2 .

It is not an unprimeable number, because it can be changed into a prime (21424049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5356009 + ... + 5356012.

Almost surely, 2^21424042 is an apocalyptic number.

21424042 is a deficient number, since it is larger than the sum of its proper divisors (10712024).

21424042 is a wasteful number, since it uses less digits than its factorization.

21424042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10712023.

The product of its (nonzero) digits is 512, while the sum is 19.

The square root of 21424042 is about 4628.6112388059. The cubic root of 21424042 is about 277.7370406512.

Adding to 21424042 its reverse (24042412), we get a palindrome (45466454).

The spelling of 21424042 in words is "twenty-one million, four hundred twenty-four thousand, forty-two".