21440444 has 6 divisors (see below), whose sum is σ = 37520784. Its totient is φ = 10720220.

The previous prime is 21440431. The next prime is 21440449. The reversal of 21440444 is 44404412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21440449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2680052 + ... + 2680059.

It is an arithmetic number, because the mean of its divisors is an integer number (6253464).

Almost surely, 2^21440444 is an apocalyptic number.

It is an amenable number.

21440444 is a deficient number, since it is larger than the sum of its proper divisors (16080340).

21440444 is a wasteful number, since it uses less digits than its factorization.

21440444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5360115 (or 5360113 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 23.

The square root of 21440444 is about 4630.3827055655. The cubic root of 21440444 is about 277.8078999986.

Adding to 21440444 its reverse (44404412), we get a palindrome (65844856).

The spelling of 21440444 in words is "twenty-one million, four hundred forty thousand, four hundred forty-four".