21842042 has 48 divisors (see below), whose sum is σ = 38195712. Its totient is φ = 9335040.

The previous prime is 21842027. The next prime is 21842083. The reversal of 21842042 is 24024812.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a junction number, because it is equal to n+sod(n) for n = 21841999 and 21842017.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 412088 + ... + 412140.

It is an arithmetic number, because the mean of its divisors is an integer number (795744).

Almost surely, 2^21842042 is an apocalyptic number.

21842042 is a deficient number, since it is larger than the sum of its proper divisors (16353670).

21842042 is a wasteful number, since it uses less digits than its factorization.

21842042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143 (or 126 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 23.

The square root of 21842042 is about 4673.5470469441. The cubic root of 21842042 is about 279.5317087307.

Adding to 21842042 its reverse (24024812), we get a palindrome (45866854).

The spelling of 21842042 in words is "twenty-one million, eight hundred forty-two thousand, forty-two".