21444380 has 12 divisors (see below), whose sum is σ = 45033240. Its totient is φ = 8577744.

The previous prime is 21444373. The next prime is 21444389. The reversal of 21444380 is 8344412.

It is a super-2 number, since 2×21444380² = 919722867168800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21444389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 536090 + ... + 536129.

It is an arithmetic number, because the mean of its divisors is an integer number (3752770).

Almost surely, 2^21444380 is an apocalyptic number.

21444380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21444380 is an abundant number, since it is smaller than the sum of its proper divisors (23588860).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21444380 is a wasteful number, since it uses less digits than its factorization.

21444380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1072228 (or 1072226 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 26.

The square root of 21444380 is about 4630.8077049258. The cubic root of 21444380 is about 277.8248987913.

Adding to 21444380 its reverse (8344412), we get a palindrome (29788792).

The spelling of 21444380 in words is "twenty-one million, four hundred forty-four thousand, three hundred eighty".