21420044 has 6 divisors (see below), whose sum is σ = 37485084. Its totient is φ = 10710020.

The previous prime is 21420043. The next prime is 21420073. The reversal of 21420044 is 44002412.

It is not an unprimeable number, because it can be changed into a prime (21420043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2677502 + ... + 2677509.

It is an arithmetic number, because the mean of its divisors is an integer number (6247514).

Almost surely, 2^21420044 is an apocalyptic number.

It is an amenable number.

21420044 is a deficient number, since it is larger than the sum of its proper divisors (16065040).

21420044 is a wasteful number, since it uses less digits than its factorization.

21420044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5355015 (or 5355013 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 21420044 is about 4628.1793396540. The cubic root of 21420044 is about 277.7197631495.

Adding to 21420044 its reverse (44002412), we get a palindrome (65422456).

The spelling of 21420044 in words is "twenty-one million, four hundred twenty thousand, forty-four".