21421244 has 12 divisors (see below), whose sum is σ = 40370904. Its totient is φ = 9886704.

The previous prime is 21421243. The next prime is 21421247. The reversal of 21421244 is 44212412.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421243) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 205922 + ... + 206025.

It is an arithmetic number, because the mean of its divisors is an integer number (3364242).

Almost surely, 2^21421244 is an apocalyptic number.

It is an amenable number.

21421244 is a deficient number, since it is larger than the sum of its proper divisors (18949660).

21421244 is a wasteful number, since it uses less digits than its factorization.

21421244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411964 (or 411962 counting only the distinct ones).

The product of its digits is 512, while the sum is 20.

The square root of 21421244 is about 4628.3089784499. The cubic root of 21421244 is about 277.7249492187.

Adding to 21421244 its reverse (44212412), we get a palindrome (65633656).

The spelling of 21421244 in words is "twenty-one million, four hundred twenty-one thousand, two hundred forty-four".